The present invention is directed to a process for separating an olefin copolymer from volatile gases using a flash separator. The flash separator can be used with a solution or high pressure process. The mass transport of volatile gases from the viscous polymer melt is increased.

The present invention is directed to a process for separating an olefin copolymer from volatile gases using a flash separator. The flash separator can be used with a solution or high pressure process. The mass transport of volatile gases from the viscous polymer melt is increased.

A dispersant for suspension polymerization may, even when a usage amount thereof is low, enable obtaining polymer particles having a small average particle diameter with few coarse particles, and having favorable plasticizer absorptivity. Such a dispersant may include a vinyl alcohol polymer having a structure of following formula (1)

##STR00001## and satisfy inequality (2)

0.4[X]10.sup.2/[R.sub.a,1].sup.23.0(2).

In formula (1), R is a hydrocarbon group having 4 or more carbon atoms. In inequality (2), [X] is a mole percentage content of the structure of formula (1) with respect to total structural units of the vinyl alcohol polymer; and [R.sub.a,1] is an HSP distance ((J/cm.sup.3).sup.1/2) between the structure of formula (1) and vinyl chloride.

A dispersant for suspension polymerization may, even when a usage amount thereof is low, enable obtaining polymer particles having a small average particle diameter with few coarse particles, and having favorable plasticizer absorptivity. Such a dispersant may include a vinyl alcohol polymer having a structure of following formula (1)

##STR00001## and satisfy inequality (2)

0.4[X]10.sup.2/[R.sub.a,1].sup.23.0(2).

In formula (1), R is a hydrocarbon group having 4 or more carbon atoms. In inequality (2), [X] is a mole percentage content of the structure of formula (1) with respect to total structural units of the vinyl alcohol polymer; and [R.sub.a,1] is an HSP distance ((J/cm.sup.3).sup.1/2) between the structure of formula (1) and vinyl chloride.

Preparation of a block copolymer comprising a polyethylene block and a block formed of the polymerization of one or more vinyl monomers, at least 50 mol % of which being selected from the list consisting of ethylene, vinyl esters, non-conjugated N-vinyl monomers, acrylonitrile, (meth)acrylates and (meth)acrylamides, at least one of said one or more vinyl monomers not being ethylene, the process comprising: polymerizing ethylene or the one or more vinyl monomers in presence of an organic cobalt complex, thereby forming a macroinitiator; contacting the macroinitiator with either; the one or more vinyl monomers, if ethylene was polymerized in step a, or; ethylene, if the one or more vinyl monomers were polymerized in step a, thereby forming a second polymer block, and thereby forming the block copolymer, wherein forming the polyethylene block is performed under a pressure above 1 bar.

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.

The present invention discloses a photosensitive composition, comprising polyvinyl acetate (0% saponified) having a styryl type nitrogen-containing heterocyclic groups such as a styrylpyridinium or/and styrylquinolinium that possesses high UV light energy sensitivity with a small photosensitive group content, high solid content, high water resistance, and very sharp imaging characteristics and produced therefrom photosensitive compositions such as a photo-resist, photolithographic plates, screen printing stencil emulsion and film, and abrasion resistant photosensitive emulsion and film, and other photosensitive compositions being used for commercial and industrial applications.

The present invention discloses a photosensitive composition, comprising polyvinyl acetate (0% saponified) having a styryl type nitrogen-containing heterocyclic groups such as a styrylpyridinium or/and styrylquinolinium that possesses high UV light energy sensitivity with a small photosensitive group content, high solid content, high water resistance, and very sharp imaging characteristics and produced therefrom photosensitive compositions such as a photo-resist, photolithographic plates, screen printing stencil emulsion and film, and abrasion resistant photosensitive emulsion and film, and other photosensitive compositions being used for commercial and industrial applications.

A polyvinyl alcohol film comprises a vinyl alcohol-based polymer, wherein, when the polyvinyl alcohol film being 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 A has a resulting relaxation time of 0.0070 milliseconds or more and 0.0092 milliseconds or less, and a resulting component ratio of 20% or more and 50% or less.