Shin-etsu Chemical Co., Ltd.

Genji Noguki

Toshihide Shimizu

Mikio Watanabe

Hajime Kitamura

Masatoshi Ishii

Hiroyuki Miyamoto

Shigehiro Hoshida

Kenichi Itoh

Tadashi Amano

Yasuhiro Takahashi

Yukihiro Kuribayashi

Motoaki Tanaka

Takashi Kobayashi

Yoshitaka Okuno

Toshimichi Koga

Masanobu Uchida

Kouzou Kuwabara

Hitoshi Ohba

Hitoshi Nakajima

Tatsuo Ishii

Masanobu Nakahara

A chargeable resin powder is transported by means of an airstream which is a mixture of air and steam. This enables pneumatic transport of chargeable resin powder without building up electrostatic charges.

Pneumatic transport of chargeable resin powder

A process for producing a polymer by polymerizing in a polymerization vessel a monomer having an ethylenic double bond is provided. In this process, the polymerization vessel has a polymer scale preventive coating film on its inner wall surfaces and other surfaces with which the monomer comes into contact during polymerization. The coating film is formed by coating a coating liquid containing (A) a compound selected from the group consisting of an aromatic compound having 5 or more conjugated &pgr; bonds and a heterocyclic compound having 5 or more conjugated &pgr; bonds, and (B) a compound selected from the group consisting of an inorganic colloid, a chelate reagent, a metal compound that produces a metal ion capable of forming a complex having at least two coordination numbers, and an acid; the coating liquid being coated by means of steam as a carrier. This process can shorten the time for forming coating films of scale preventive agents to improve productivity, can improve the effect of preventing polymer scales, can make colored particles less which mix into polymer products, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

Process for producing a polymer by polymerization of a monomer having an ethylenic double bond

A process for producing a polymer by polymerizing in a polymerization vessel a monomer having an ethylenic double bond is provided. In this process, the polymerization vessel has a polymer scale preventive coating film on its inner wall surfaces and other surfaces with which the monomer comes into contact during polymerization. The coating film is formed by coating a first coating liquid containing a compound selected from the group consisting of an aromatic compound having 5 or more conjugatedbonds and a heterocyclic compound having 5 or more conjugatedbonds and a second coating liquid containing at least one hydrophilic compound selected from the group consisting of a water-soluble polymeric compound, an inorganic colloid, an inorganic salt and an acid; the first coating liquid and the second coating liquid being simultaneously coated by means of steam as a carrier. This process can shorten the time for forming coating films of scale preventive agents to improve productivity, can improve the effect of preventing scales, can make colored particles less mix into polymer products obtained by this process, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

An improved process for producing a polymer by polymerizing a monomer having an ethylenic double bond in a polymerization vessel having a polymer scale preventive coating film on its inner wall surfaces, etc. is provided. The coating film is formed by coating a first coating liquid containing a compound selected from the group consisting of an aromatic compound having 5 or more conjugated &pgr; bonds and a heterocyclic compound having 5 or more conjugated &pgr;bonds, and then coating a second coating liquid a dye and/or pigment on the first layer. The first and second coating liquids are applied by means of steam as a carrier. The second layer has a surface having a contact angle to water of less than 60&deg; after its surface has been kept in contact with a solution of mixture of water and a vinyl chloride monomer in a weight ratio of 1:1 at 50&deg; C. for 1 hour. This process can shorten the time for forming the coating film to improve productivity, can improve the effect of preventing adhesion of polymer scale, can make colored particles less mix into polymer products obtained by this process, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

A method for making hydrogen storage alloy powder comprises quenching a melt of a hydrogen storage alloy, breaking the quenched alloy into fine pieces provided that said alloy is in non-powder form after the quenching, and subjecting the fine pieces to treatment with a solution containing a conjugated unsaturated compound which has five or more conjugated &pgr; bonds in the molecule and a molecular weight of 100 or above.

Method for making hydrogen storage alloy powder and electrode comprising the alloy powder

A vinyl chloride polymer is prepared by charging a reactor with a vinyl chloride monomer, effecting polymerization, removing a slurry of the polymer from the reactor, and washing the reactor interior with water, and repeating the series of steps. The reactor has an internal volume of at least 40 m,. A cylinder-guided lift type washer assembly having a nozzle is secured to the reactor at its top in a sealed manner such that the nozzle can be moved downward and upward in the reactor. Water is fed to the nozzle through the assembly for injecting water from the nozzle into the reactor for cleaning. The large size reactor can be effectively washed with water in the closed state, and vinyl chloride polymers of quality with least fisheyes are produced batchwise, leading to an improved productivity.

Preparation of vinyl chloride polymer

An improved process for producing a polymer by polymerizing a monomer having an ethylenic double bond in a polymerization vessel having a polymer scale preventive coating film on its inner wall surfaces, etc. is provided. The coating film is formed by coating a first coating liquid containing a compound selected from the group consisting of an aromatic compound having 5 or more conjugated .pi. bonds and a heterocyclic compound having 5 or more conjugated .pi. bonds, and then coating a second coating liquid on the first layer. The first and second coating liquids are applied by means of steam as a carrier. The second layer has a surface having a contact angle to water of less than 60.degree. after its surface has been brought into contact with a solution of mixture of water and a vinyl chloride monomer in a weight ratio of 1:1, at 50.degree. C. for 1 hour. This process can shorten the time for forming the coating film to improve productivity, can improve the effect of preventing adhesion of polymer scale, can make colored particles less mix into polymer products obtained by this process, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

Process for producing a polymer by polymerization of a monomer having an

A powder of a hydrogen storage alloy which comprises metallic nickel in or on the surfaces of the powder in an amount sufficient to impart a magnetization intensity of 0.5 to 6 emu/g to the powder. The powder has a specific surface area of 0.15 to 0.7 m.sup.2 /g when determined according to a BET adsorption method, an oxygen concentration of 0.15 to 1.5 wt %, and an average particle size of 10 to 100 .mu.m, with a size distribution wherein the content of particles having a size of 8 .mu.m or below is in the range of 30 wt % or below. An electrode for secondary cells is also described, which comprises the powder defined above.

Hydrogen storage alloy powder and an electrode comprising the same

A method of producing a hydrogen absorbing alloy powder, which comprises a step of treating a pulverized hydrogen absorbing alloy with a solution comprising a conjugated unsaturated compound having at least 5 conjugated .pi. bonds and a molecular weight of at least 100 and, prior to the this step, optionally comprises a step of treating a pulverized hydrogen absorbing alloy with a mineral acid or alkali; and an electrode using a hydrogen absorbing alloy powder produced by the aforesaid method.

Method of producing hydrogen absorbing alloy powder, and electrode using

The present invention provides a method of producing vinyl chloride polymers, including the steps of subjecting vinyl chloride monomer or a mixture of monomers containing vinyl chloride monomer to suspension polymerization reaction in an aqueous medium within a polymerization vessel equipped with a reflux condenser, and subsequently, after the completion of the polymerization reaction, recovering any unreacted monomer, wherein foam generated on the surface of the liquid phase inside the polymerization vessel is eliminated by discharging a high pressure water having a pressure of 20 kg/cm.sup.2 or more substantially linearly to the surface of the liquid phase. The high pressure water discharging is carried out at the polymerization step, particularly from the time when operation of the reflux condenser begins, and/or at the recovery step. A vinyl chloride polymer is thus obtained without the splashing of foam over the gaseous phase section of the polymerization vessel, regardless of whether the heat removal rate of the reflux condenser, or the recovery rate per unit time for the unreacted monomer are increased.

Method of removing foam during polymerization of vinyl chloride polymers

An improvement is proposed for decreasing triboelectric static charging of a polyvinyl chloride resin powder so as to improve the flowability of the powder and prevent a decrease in the bulk density of the powder due to static electricity. The improvement comprises, in the polymerization process of vinyl chloride monomer in an aqueous medium, adding, to the aqueous polymerization mixture, a specified amount of an aqueous dispersion containing a salt of a long-chain carboxylic acid with a divalent metal and an ester of sorbitan with a long-chain carboxylic acid in a specified weight proportion and in a specified total concentration at a moment when conversion of the monomer to polymer is at least 70%.

Method for the preparation of a polyvinyl chloride resin powder with

Foaming above the aqueous polymerization mixture can be efficiently reduced in suspension polymerization of vinyl chloride monomer in an aqueous medium contained in a polymerization reactor equipped with a reflux condenser for removal of the heat of polymerization by admixing the polymerization mixture with additives comprising (a) from 0.002 to 0.007 part by weight of a partially saponified polyvinyl alcohol having a degree of saponification in the range from 20 to 50% by moles and an average degree of polymerization in the range from 200 to 400 and (b) from 0.001 to 0.01 part by weight of a silicone-based defoaming agent, each amount being per 100 parts by weight of the vinyl chloride monomer or the monomer mixture mainly composed of vinyl chloride, at a moment, preferably, before the reflux condenser is brought into operation. By this improvement, the resultant polyvinyl chloride resin product may have a greatly improved bulk density and particle size distribution without causing polymer scale deposition on the reactor walls.

Method for reducing foaming in a vinyl chloride polymerization reactor

The invention provides an improvement in the suspension polymerization of vinyl chloride in an aqueous medium in the presence of a monomer-soluble polymerization initiator, according to which the amount of polymer scale deposition on the reactor walls can be greatly decreased. The improvement comprises admixing the aqueous polymerization medium with (a) a water-soluble crosslinked copolymer of an unsaturated carboxylic acid monomer, e.g. acrylic acid, and a crosslinking monomer such as di(methyl)allyl ether of diethyleneglycol and (b) a non-ionic surface active agent in combination.

Method for the polymerization of vinyl chloride monomer in an aqueous

The invention provides an improvement in the suspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in an aqueous medium containing a nonionic surface active agent and in the presence of a monomer-soluble polymerization initiator, according to which the aqueous polymerization medium is admixed with a crosslinked copolymer having carboxyl groups such as a copolymer of acrylic acid and diethyleneglycol bisallyl or bismethallyl ether at a moment when the percentage of the monomer conversion is in the range from 1 to 20% so that a polyvinyl chloride resin product of high quality can be obtained having an outstandingly high bulk density and plasticizer absorptivity but still containing an extremely small number of fish eyes.

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Itako-machi, Japan

Genji Noguki