摘要:
The present invention provides a method for producing a polymer by conducting polymerization in a polymerization reactor having an inner wall covered with an anti-fouling agent comprising an aqueous solution containing a polyvinyl alcohol obtained through saponification of a polyvinyl ester that contains monomer units having a silyl group. In the present invention, the polyvinyl alcohol satisfies the following formulae (I) and (II): 370
摘要:
Disclosed is an anti-fouling agent which is superior in viscosity stability, water resistance of its film and ability of preventing a scale from depositing on the inner wall of a polymerization reactor and which can prevent the contamination of foreign substances into a polymeric product caused by exfoliation of a scale depositing on the inner wall of a polymerization reactor and exfoliation of the anti-fouling agent itself, the anti-fouling agent comprising an aqueous solution containing a polyvinyl alcohol that is obtained through saponification of a polyvinyl ester that contains monomer units having a specific silyl group and that satisfies the following formulae (I) and (II): 370
摘要:
The present invention provides a method for producing a polymer by conducting polymerization in a polymerization reactor having an inner wall covered with an anti-fouling agent comprising an aqueous solution containing a polyvinyl alcohol obtained through saponification of a polyvinyl ester that contains monomer units having a silyl group. In the present invention, the polyvinyl alcohol satisfies the following formulae (I) and (II): 370
摘要:
Vinyl alcohol polymers having an ethylene unit content of 2 to 19 mole %, a polymerization degree of 200 to 2,000, a degree of saponification of 80 to 99.99 mole % and a total content of carboxyl group and lactone rings of 0.02 to 0.4 mole % are excellent in thermal stability, water resistance, gas-barrier properties, water vapor-barrier property, stability of aqueous solution kept at low temperatures and biodegradability.
摘要:
A water-soluble resin composition is provided which comprises (i) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of at least 90 mole percent, (ii) 1 to 50 parts by weight of a plasticizer and (iii) 5 to 50 parts by weight of a monosaccharide and/or a polysaccharide, optionally together with (iv) 1 to 20 parts by weight of an inorganic filler. Also provided is a water-soluble resin composition which comprise (i′) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of 92 to 99 mole percent, (ii′) 1 to 50 parts by weight of a plasticizer and (iv′) 1 to 20 parts by weight of an inorganic filler, optionally together with (iii′) 5 to 50 parts by weight of a monosaccharide and/or polysaccharide. Further provided are water-soluble films produced by using those water-soluble resin compositions.
摘要:
The present invention provides polyvinyl alcohol based (PVA) whose solubility in water varies with a small temperature change to a sufficiently great degree. In manufacturing a polyvinyl alcohol based polymer by: progressing a transesterification reaction of a polyvinyl ester based polymer with alcohol in a liquid reaction mixture including the polyvinyl ester based polymer, the alcohol, and a basic compound; precipitating the polyvinyl ester based polymer, at least a part of which has been transesterified with the alcohol, out of the liquid reaction mixture; and further progressing the transesterification reaction in the liquid reaction mixture including the polyvinyl ester based polymer that has precipitated, the liquid reaction mixture has a temperature of 75° C. to 150° C. when the polyvinyl ester based polymer, at least a part of which has been transesterified, starts precipitating.
摘要:
A vinyl alcohol polymer with a side chain being a hydroxyalkyl group having 2 to 20 carbon atoms is disclosed. Conventional water-soluble vinyl alcohol polymers gives, where they have a high interfacial activity, an aqueous solution with much-foaming and hence a problem when used for commercial purposes. On the other hand, the vinyl alcohol polymer of the present invention gives, where it is water-soluble, an aqueous solution with less-foaming in spite of its high interfacial activity, and hence an excellent industrial applicability. The vinyl alcohol polymer of the present invention is useful as thermoplastic resin and dispersion stabilizer. In addition, the vinyl alcohol polymer of the present invention is usable for various purposes, e.g. surfactants for various uses, paper coating agent, quality-improving agent for paper such as paper ingredients and pigment binders, adhesive for wood, paper, aluminum foil and inorganic materials, binder for nonwoven fabric, paint, warp sizing agent, fiber-processingagent, sizing agent for hydrophobic fibers such as polyester fiber, various films and sheets, bottles and fibers.
摘要:
A polyvinyl alcohol having hydrolyzed silyl group functionalized monomer units. The polyvinyl alcohol satisfies the following formulae (I) and (II) and the pH of an aqueous 4% solution of the polyvinyl alcohol is between 4 and 8: 20
摘要:
The invention provides a polyvinyl acetal having a degree of acetalization of from 45 to 80 mol %, which is obtained through acetalization of a polyvinyl alcohol having a degree of polymerization of from 30 to 1000 and a degree of hydrolysis of from 80.0 to 99.99 mol % and having a specific amount of an ionic group bonded to the terminal thereof via a sulfido bond. The polyvinyl acetal of the invention is useful for binders for ceramic forming and for binders for ink or paint.
摘要:
A polymer electrolyte membrane comprising as a main ingredient a block copolymer (P) which comprises, as its constituents, a vinyl alcoholic polymer block (A) and a polymer block (B) having ion-conducting groups, which block copolymer(P) is cross-linking treated, and a membrane-electrode assembly and a fuel cell using the polymer electrolyte membrane, respectively. Preferred as polymer block (B) is one having a styrene or vinylnaphthalene skeleton or a 2-(meth)acrylamido-2-methylpropane skeleton. The ion-conducting group includes a sulfonic acid group, a phosphonic acid group or the like.