This invention relates to imageable polymers, particularly those comprising poly vinylalcohol and to methods for making them as well as to embolic microspheres comprising the polymers. The microspheres are imageable during embolization procedures and can be loaded with drugs or other therapeutic agents to provide an imageable drug delivery system.

Provided is a secondary battery electrode additive with which an active material can be coated without heat treatment that is performed at a high temperature for a long period of time, an alkaline component can be neutralized, and the decomposition of an electrolytic solution can be suppressed. For example, provided is a secondary battery electrode additive comprising a boronic acid derivative represented by formula (5).

##STR00001##

(In the formula, R.sup.1-R.sup.5 each independently represent a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxy group, and R.sup.6 represents a hydrogen atom, a methyl group, or an ethyl group.)

Provided is a secondary battery electrode additive with which an active material can be coated without heat treatment that is performed at a high temperature for a long period of time, an alkaline component can be neutralized, and the decomposition of an electrolytic solution can be suppressed. For example, provided is a secondary battery electrode additive comprising a boronic acid derivative represented by formula (5).

##STR00001##

(In the formula, R.sup.1-R.sup.5 each independently represent a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxy group, and R.sup.6 represents a hydrogen atom, a methyl group, or an ethyl group.)

A polyvinyl alcohol film comprising a vinyl alcohol-based polymer, wherein, when the polyvinyl alcohol film is measured by a solid echo method using pulse NMR at 80 C. for waveform separation of a free induction decay curve of 1H spin-spin relaxation into three curves derived from three components a component A, a component B, and a component C in order of short relaxation time, the component A has a resulting relaxation time of 0.0083 milliseconds or more and 0.0093 milliseconds or less, and a resulting component ratio of 10% or more and 35% or less.

A polyvinyl alcohol film comprising a vinyl alcohol-based polymer, wherein, when the polyvinyl alcohol film is measured by a solid echo method using pulse NMR at 80 C. for waveform separation of a free induction decay curve of 1H spin-spin relaxation into three curves derived from three components a component A, a component B, and a component C in order of short relaxation time, the component A has a resulting relaxation time of 0.0083 milliseconds or more and 0.0093 milliseconds or less, and a resulting component ratio of 10% or more and 35% or less.

A preparation method of PVA fiber comprises the following steps: preparing a spinning dope; PVAc is used as a raw material, and dissolved with addition of methanol before filtration, and then the spinning dope is obtained; spinning; the spinning dope is injected into a spinneret, and the ejected fibers are brought into a direct current electrolytic cell, and undergo a series of reactions of alcoholysis, electrolytic catalytic alcoholysis, and the levering of the alcohol; and the solution formulation in the electrolytic coagulation bath comprises alkali, alcohol and water; acid bath; through stretching, drying, washing with water, crimping with hot water and packaging, a finished polyvinyl alcohol fiber product is formed. The mirabilite is not needed in the coagulation bath, and PVA is obtained by the alcoholysis of PVAc in an electrolytic cell, and the produced PVA fibers present high purity and few impurities.

A preparation method of PVA fiber comprises the following steps: preparing a spinning dope; PVAc is used as a raw material, and dissolved with addition of methanol before filtration, and then the spinning dope is obtained; spinning; the spinning dope is injected into a spinneret, and the ejected fibers are brought into a direct current electrolytic cell, and undergo a series of reactions of alcoholysis, electrolytic catalytic alcoholysis, and the levering of the alcohol; and the solution formulation in the electrolytic coagulation bath comprises alkali, alcohol and water; acid bath; through stretching, drying, washing with water, crimping with hot water and packaging, a finished polyvinyl alcohol fiber product is formed. The mirabilite is not needed in the coagulation bath, and PVA is obtained by the alcoholysis of PVAc in an electrolytic cell, and the produced PVA fibers present high purity and few impurities.

The present invention relates to a polyvinyl alcohol film comprising a vinyl alcohol-based polymer, wherein, when the polyvinyl alcohol film is measured by a solid echo method using pulse NMR at 60 C. for waveform separation of a free induction decay curve of 1H spin-spin relaxation into three curves derived from three components a component A, a component B, and a component C in order of short relaxation time, the component B has a resulting relaxation time of 0.03 milliseconds or more and 0.05 milliseconds or less, and a resulting component ratio of 30% or more and 50% or less. From the polyvinyl alcohol film according to the present invention, a polarizing film having good polarization performance can be manufactured without the occurrence of unevenness of dyeing.

The present invention relates to a polyvinyl alcohol film comprising a vinyl alcohol-based polymer, wherein, when the polyvinyl alcohol film is measured by a solid echo method using pulse NMR at 60 C. for waveform separation of a free induction decay curve of 1H spin-spin relaxation into three curves derived from three components a component A, a component B, and a component C in order of short relaxation time, the component B has a resulting relaxation time of 0.03 milliseconds or more and 0.05 milliseconds or less, and a resulting component ratio of 30% or more and 50% or less. From the polyvinyl alcohol film according to the present invention, a polarizing film having good polarization performance can be manufactured without the occurrence of unevenness of dyeing.

A modified ethylene-vinyl alcohol copolymer fiber includes an ethylene-vinyl alcohol copolymer containing 0.1 to 10 mol % of a modified component and 5 to 55 mol % of ethylene, and has a crystallinity of 25% to 50%.