Abstract: This invention relates to a process for producing an .alpha.-olefin polymer having a high stereoregularity in a high yield by polymerizing .alpha.-olefin in the presence of a catalyst composed of solid catalyst component (I) prepared by contacting (A) magnesium halide, (B) aromatic carboxylic acid ester, (C) halogen compound of titanium, and (D) siloxyaluminum compound with each other, and (II) an organometallic compound of a metal of Group I to III in the Periodic Table.

Abstract: A process for producing olefin polymers comprising contacting an ethylenically unsaturated monomer comprising at least one olefin monomer with a catalyst system comprising a combination of a catalyst component I and a catalyst component II as described hereunder:Catalyst component IA solid product obtained by contacting the following constituents (a), (b) and (c) or (a), (b), (c) and (d) together:(a) A solid reaction product of a magnesium compound containing a hydroxyl group attached to magnesium and an organoaluminum compound represented by the formula R.sub.n AlX.sub.3-n wherein R represents a hydrocarbon residue having from 1 to 20 carbon atoms, X represents a halogen atom and n represents a number of greater than zero but not greater than 1.5, i.e. 0<n.ltoreq.1.

Abstract: A polyester resin composition having excellent mechanical properties, processability, transparency and surface glossiness of the formed product thereof, which comprises 1 to 99% by weight of an aromatic polyester produced by polycondensing para-hydroxybenzoic acid or a functional derivative thereof (I), 2,2-bis(4'-hydroxyphenyl)propane or a functional derivative thereof (II), and terephthalic acid or a functional derivative thereof (III) and/or isophthalic acid or a functional derivative thereof (IV) in a molar ratio of (I):(II)=1:100 to 100:1 and (II):(III) and/or (IV)=1:10 to 10:1 and 99 to 1% by weight of a polycarbonate or an aliphatic polyester.

Abstract: A novel resin composition is obtained by blending a hydrophilic pullulan with 2 to 98 wt %, based on the total resin weight, of a hydrophobic thermoplastic resin.In case the amount of the thermoplastic resin is 2 to 50 wt %, there is obtained a resin composition consisting essentially of the pullulan which is excellent in water resistance, while in case the amount of the thermoplastic resin is 50 to 98 wt %, there is obtained a resin composition consisting essentially of the thermoplastic resin which has been improved in water and moisture absorptivity.

Abstract: In a rotary head type magnetic tape video recording-reproducing device of the type in which a magnetic tape from a supply reel is wrapped around a rotary drum carrying magnetic heads along the path of revolution thereof at an angle other than 0.degree. relative to the axis of rotation of said rotary drum, and is taken up by a take-up reel for recording or reproducing, when a stop button is depressed or the power supply to a take-up reel driving motor is interrupted, the motor is stopped and then immediately reversed in direction for a predetermined time, thereby loosening the tension of the magnetic tape. This arrangement prevents the adhesion of the magnetic tape to the surfaces of the magnetic tape passages, especially of the rotary drum, due to the moisture or the condensation of vapor so that the smooth re-starting of the magnetic tape may be ensured.

Abstract: A foamed plastic of a resin composition comprising a pullulan type resin and a thermoplastic resin.When a resin composition comprising a pullulan type resin and a thermoplastic resin is foamed, the resulting foamed plastic is improved in moisture and water absorptivity which is low in the case of a foamed plastic composed of the thermoplastic resin, and in water resistance which is low in the case of a foamed plastic composed of the pullulan type resin.

Abstract: A tape cassette for a helical scan type recording and reproducing apparatus comprising upper and lower cylindrical members capable of engaging with each other and adapted to accept a magnetic head therein, and movable poles connected with the upper cylindrical members and capable of stretching a tape outward to prevent contact with various parts of the recording and reproducing apparatus in loading and retrieving the tape cassette. The upper cylindrical member has a helical projection to engage with a helical groove formed in a support member so that it moves also vertically with the rotation thereof so as to expose the magnetic head and take up the tape.