Kureha Kagaku Kogyo Kabushiki Kaisha

Kureha Chemical Industry Company, Limited

Hideki Wakamori

Kunizoh Kidoh

Fujio Suzuki

Katsuo Horie

Takao Iwasaki

Hidetora Kashio

Kazuo Kusida

Kamizo Iimura

Genzo Asai

This invention provides PVDF having such crystallization properties as to produce small spherulite sizes without sacrifices to properties, processability, purity, etc., and a suspension polymerization method to obtain the same. The PVDF obtained by this invention comprises the monomer unit content of 99.5-96 wt. % of vinylidene fluoride, and the monomer unit content of 0.5-4 wt. % of comonomers selected from hexafluoropropylene and/or tetrafluoroethylene, and has a logarithmic viscosity of 0.9-1.3 dl/g, and a molecular-weight distribution, as expressed in the ratio (Mw/Mn) of weight-average molecular weight and number-average molecular weight, of 2.2-2.8. In order to manufacture the PVDF of this invention, a mixture of vinylidene fluoride monomers containing 1-5 wt. % of monomers selected from hexafluoropropylene and/or tetrafluoroethylene is suspension-polymerized in an aqueous medium, using an oil-soluble initiator so that the logarithmic viscosity [.eta..sub.1 ] is kept at 1.3-1.9 dl/g until the polymerization conversion rate of vinylidene fluoride monomers becomes 10-50%, and the polymerization is continued by adding a chain transfer agent at that polymerization conversion rate so that the logarithmic viscosity [.eta..sub.2 ] of the eventually obtained polymers becomes 0.3-0.7 dl/g lower than [.eta..sub.1 ], and yet remains in the range of 0.9-1.3 dl/g.

Vinylidene fluoride polymer and method of making same

Polyvinylidene fluoride (PVDF) having such crystallization properties as to produce small spheralite sizes without sacrificing properties, processability, purity, etc. comprises 99.5-96 wt. % of vinylidene fluoride and 0.5-4 wt. % of a comonomer selected from the group consisting of hexafluoropropylene, tetrafluoroethylene and mixtures thereof, has a logarithmic viscosity of 0.9-1.3 dl/g and a molecular weight distribution, as expressed by the ratio of weight average molecular weight to number average molecular weight, of 2.2-2.8. The PVDF is formed by suspension polymerizing vinylidene fluoride and 1-5 wt. % of the desired comonomer, in an aqueous medium in the presence of an oil-soluble initiator, so that a logarithmic viscosity [.eta..sub.1 ] of 1.3-1.9 dl/g is obtained at a vinylidene fluoride conversion of 10-50%; then adding a chain transfer agent to the medium and continuing polymerization so that the logarithmic viscosity [.eta..sub.2 ] of the final polymer is 0.3-0.7 dl/g lower than [.eta..sub.1 ] but remains in the range of 0.9-1.3 dl/g.

Fine particles of polyvinyl chloride produced by bulk polymerization which comprise substantially discrete spherical particles with particle sizes of 0.2 to 2 microns, a plastisol prepared by adding 80 parts by weight of dioctylphthalate to 100 parts by weight of said particles having a viscosity of 50,000 centipoise or less (measured by a B-type viscometer, No. 4 rotor, 12 rpm, 25.degree. C.) and a process for producing the same which comprises subjecting vinyl chloride to bulk polymerization in the presence of a dispersing stabilizer under gentle stirring without causing sedimentation or agglomeration of the polymer particles formed, wherein polymerization is terminated at a polymerization yield of 5 to 30%.

Fine particles of polyvinyl chloride and process for producing the same

A suspension polymerization of a haloethylene compound or a mixture of a haloethylene compound and a comonomer thereof is carried out in an aqueous medium containing a suspending agent and an oil soluble catalyst, by coating or incorporating at least one of a water soluble or organic solvent soluble lignin derivative.

Suspension polymerization of haloethylene compound

A plasticized vinylidene chloride-vinyl chloride copolymer is produced by copolymerizing 65 to 95 wt. % of vinylidene chloride and 35 to 5 wt. % of vinyl chloride or a mixture of vinyl chloride as a main component and a comonomer wherein 0.5 to 10.0 wt. parts of a plasticizer being soluble in said monomer mixture is added to 100 wt. parts of said monomer mixture and said monomer mixture is copolymerized by a suspension polymerization in the presence of an oil soluble radical initiator and a macromolecular suspending agent in water whereby a blending step can be eliminated.

Process for producing plasticized vinylidene chloride-vinyl chloride

A suspension of a particulate porous fluorinated resin in an aqueous medium containing a powder of an inorganic suspension stabilizer is heated approximately at a melting temperature of the resin whereby the resin is densified, the degree of densification of the resin depending on the heating temperature.

Densification of particulate porous fluorinated resins

From a synthesized high polymer latex, the unreacted monomer remaining therein can be removed efficiently by causing a hollow cylinder inclined by a gradient of 1/100 to 1/10 with reference to the horizontal plane to be rotated around its axis, then introducing the synthesized high polymer latex and a gas containing moisture into the interior of the hollow cylinder which is maintained in continuous rotation and allowing the latex and the gas to come into mutual contact within the hollow cylinder.

Growing community of inventors

Iwaki, Japan

Hideki Wakamori