Abstract: A method for residual monomer diminution by which a residual monomer is speedily removed from an N-vinyl compound polymer or the like without posing a problem such as an increase in ash content; and a process for producing an N-vinyl compound polymer solution or powder which has a regulated pH and is free from a decrease in pH with time. The method comprises adding an organic acid having a boiling point of 140° C. or higher at ordinary pressure to anaqueous solution of an N-vinyl compound polymer. The process comprises adding an organic base to an aqueous N-vinyl compound polymer solution having a pH lower than 7.0 to thereby neutralize the solution and regulate the pH thereof. Those operations are conducted in a reaction vessel in which a gaseous phase is regulated so as to have an oxygen concentration of 5.0% by volume or lower.

Abstract: The residual amount of a solvent in a water soluble nonionic alkylene oxide resin is decreased in an apparatus including an evaporation vessel and a stirring blade which scrapes-up and coats resin solution onto the inner wall surface of the evaporation vessel. A water soluble nonionic alkylene oxide resin having a crystallization temperature of 10 to 60° C. is extruded to a predetermined thickness in a molten state, the extruded molten resin is brought into contact with a metal surface which is at the crystallization temperature (Tc) or lower, and the thereby solidified resin may be cut into pellets. The resin pellets preferably are of rectangular shape and prescribed dimensions. The resin may be pulverized in a pulverizer by shearing force between a rotary blade and a fixed blade. In the pulverizer, grains smaller than a predetermined size pass through the screen, while larger grains are again pulverized.

Abstract: An object of the present invention is to provide a process which can produce, easily and with good productivity and reproducibility, an ethylene oxide copolymer provided with desired compositional ratios of monomers and a desired molecular weight and further with a desired melting point. As a means of achieving this object, a process according to the present invention for production of an ethylene oxide copolymer is a process comprising a step of polymerizing a monomer mixture including ethylene oxide as a main component, thereby producing the ethylene oxide copolymer, with the process being characterized in that the polymerization step includes at least one step each of the following steps: a step in which only the ethylene oxide is supplied to thus polymerize it; and a step in which the ethylene oxide and another monomer are supplied to thus polymerize them.

Abstract: The present invention provides a production process, in which, when an ethylene oxide copolymer is obtained, conditions for obtaining this copolymer having a desirable molecular weight with ease and good reproducibility are provided. The production process for an ethylene oxide copolymer, according to the present invention, comprises the step of carrying out polymerization of a monomer mixture under stirring in a solvent, thereby obtaining the ethylene oxide copolymer, wherein the monomer mixture includes ethylene oxide and a substituted oxirane compound of a structural formula (1) as essential raw materials; with the production process being characterized in that the stirring is carried out by a stirring power of not less than 0.6 kW/m3.

Abstract: A method for residual monomer diminution by which a residual monomer is speedily removed from an N-vinyl compound polymer or the like without posing a problem such as an increase in ash content; and a process for producing an N-vinyl compound polymer solution or powder which has a regulated pH and is free from a decrease in pH with time.

Abstract: A method for residual monomer diminution by which a residual monomer is speedily removed from an N-vinyl compound polymer or the like without posing a problem such as an increase in ash content; and a process for producing an N-vinyl compound polymer solution or powder which has a regulated pH and is free from a decrease in pH with time. The method comprises adding an organic acid having a boiling point of 140° C. or higher at ordinary pressure to an aqueous solution of an N-vinyl compound polymer. The process comprises adding an organic base to an aqueous N-vinyl compound polymer solution having a pH lower than 7.0 to thereby neutralize the solution and regulate the pH thereof. Those operations are conducted in a reaction vessel in which a gaseous phase is regulated so as to have an oxygen concentration of 5.0% by volume or lower.

Abstract: The present invention provides a production process, in which, when an ethylene oxide copolymer is obtained, conditions for obtaining this copolymer having a desirable molecular weight with ease and good reproducibility are provided. The production process for an ethylene oxide copolymer, according to the present invention, comprises the step of carrying out polymerization of a monomer mixture under stirring in a solvent, thereby obtaining the ethylene oxide copolymer, wherein the monomer mixture includes ethylene oxide and a substituted oxirane compound of a structural formula (1) as essential raw materials; with the production process being characterized in that the stirring is carried out by a stirring power of not less than 0.6 kW/m3.

Abstract: The present invention provides: a vinylpyrrolidone polymer which exhibits good heat resistance and storage stability; a composition containing the vinylpyrrolidone polymer; a stabilization process for the vinylpyrrolidone polymer, and a preservation process for a vinylpyrrolidone polymer by which: even when the vinylpyrrolidone polymer is preserved for a long time or at high temperature, the physical properties such as molecular weight (K value) of the vinylpyrrolidone polymer can be prevented from changing, therefore the vinylpyrrolidone polymer can stably be preserved. To enhance the heat resistance and the storage stability, a vinylpyrrolidone polymer is mixed with a certain amount of antioxidant, and the oxygen concentration is suppressed to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer when preserving.

Abstract: The present invention provides a production process for a vinylpyrrolidone polymer which process prevents the polymerization reaction of N-vinylpyrrolidone from being hindered by by-products (as formed by nucleomethylation of N-vinylpyrrolidone) or &ggr;-butyrolactone, and therefore enables to obtain a vinylpyrrolidone polymer that has a desired molecular weight and involves only a small amount of residual monomers, wherein the vinylpyrrolidone polymer can display excellent properties even if the vinylpyrrolidone polymer is, for example, crosslinked to convert it into a water-absorbent resin. The production process for a vinylpyrrolidone polymer comprises the step of polymerizing a polymerizable monomer component or components which include N-vinylpyrrolidone, wherein: the N-vinylpyrrolidone as used is N-vinylpyrrolidone having a &ggr;-butyrolactone content of not more than 500 ppm; and/or the N-vinylpyrrolidone as used is N-vinylpyrrolidone obtained without using acetylene as a raw material.

Abstract: The present invention provides: a vinylpyrrolidone polymer which exhibits good heat resistance and storage stability; a composition containing the vinylpyrrolidone polymer; a stabilization process for the vinylpyrrolidone polymer, and a preservation process for a vinylpyrrolidone polymer by which: even when the vinylpyrrolidone polymer is preserved for a long time or at high temperature, the physical properties such as molecular weight (K value) of the vinylpyrrolidone polymer can be prevented from changing, therefore the vinylpyrrolidone polymer can stably be preserved. To enhance the heat resistance and the storage stability, a vinylpyrrolidone polymer is mixed with a certain amount of antioxidant, and the oxygen concentration is suppressed to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer when preserving.

Abstract: A method for residual monomer diminution by which a residual monomer is speedily removed from an N-vinyl compound polymer or the like without posing a problem such as an increase in ash content; and a process for producing an N-vinyl compound polymer solution or powder which has a regulated pH and is free from a decrease in pH with time.

Abstract: The present invention provides: a vinylpyrrolidone polymer which exhibits good heat resistance and storage stability; a composition containing the vinylpyrrolidone polymer; a stabilization process for the vinylpyrrolidone polymer, and a preservation process for a vinylpyrrolidone polymer by which: even when the vinylpyrrolidone polymer is preserved for a long time or at high temperature, the physical properties such as molecular weight (K value) of the vinylpyrrolidone polymer can be prevented from changing, therefore the vinylpyrrolidone polymer can stably be preserved. To enhance the heat resistance and the storage stability, a vinylpyrrolidone polymer is mixed with a certain amount of antioxidant, and the oxygen concentration is suppressed to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer when preserving.

Abstract: The present invention provides a production process for a vinylpyrrolidone polymer which process prevents the polymerization reaction of N-vinylpyrrolidone from being hindered by by-products (as formed by nucleomethylation of N-vinylpyrrolidone) or &ggr;-butyrolactone, and therefore enables to obtain a vinylpyrrolidone polymer that has a desired molecular weight and involves only a small amount of residual monomers, wherein the vinylpyrrolidone polymer can display excellent properties even if the vinylpyrrolidone polymer is, for example, crosslinked to convert it into a water-absorbent resin. The production process for a vinylpyrrolidone polymer comprises the step of polymerizing a polymerizable monomer component or components which include N-vinylpyrrolidone, wherein: the N-vinylpyrrolidone as used is N-vinylpyrrolidone having a &ggr;-butyrolactone content of not more than 500 ppm; and/or the N-vinylpyrrolidone as used is N-vinylpyrrolidone obtained without using acetylene as a raw material.

Abstract: A process for producing a high-molecular-weight polydioxolane, which includes the steps of: polymerizing 1,3-dioxolane using a polymerization catalyst comprising a heteropolyacid and a ketone; and neutralizing the resulting polymerization reaction product using an organic amine and/or ammonia. A hydrophilic film, which includes a resin including a polydioxolane and having a particular molecular weight and has a particular crystallinity and a particular spherulite's size. A film crumbly in cold water is produced by forming a film under particular forming conditions from a resin including a polydioxolane and having a particular molecular weight, or by subjecting an already formed film to particular thermal hysteresis.