Applications by Grades

PVOH is often used as a dispersing stabilizer for the suspension polymerization of vinyl chloride monomer (VCM). The surface active performance in relation to vinyl monomers can be widely optimized by selecting the appropriate grade of PVOH characterized by its polymerization and saponification degree.

The suspension polymerization of VCM is a technique used to produce PVC whose particle size ranges from 50 to 200 μ VCM is suspended in water by means of stirring and use of a dispersing agent and allowing a polymerization reaction to continue for several hours. The powder properties of the resultant PVC, including the size and shape of particles and bulk density, vary depending on the particle forming process during the polymerization.

The role of PVOH in the particle forming process, governing the powder properties of PVC, is very critical. 50 to 80% of the powder properties of PVC depends on the surface activity performance of PVOH.

Furthermore, the properties required of a dispersing agent are constantly changing. For instance, the speed of polymerization has been increasingly high thanks to improved heat removal efficiency during the suspension polymerization process. Therefore, the need is mounting for a PVOH capable of satisfying requirements in both productivity and environmental protection, without limiting performance, for example, the residual VCM removal performance.

To respond to a diversity of requests from the market, Nippon Gohsei offers a full line of proprietary dispersants for suspension polymerization of VCM (primary dispersant, secondary dispersant) that have a wide variety of surface active properties.

Primary Dispersants

Table of Primary Dispersants
Grade Saponification Degree (mol % ) Viscosity (mPas, 4 % ) Properties
G Type GH-23 86.5-89.0 48-56 For high BD
GH-20 86.5-89.0 40-46
GH-17 86.5-89.0 27-33
K Type KH-20 78.5-81.5 44-52 Good polymerization stability
KH-17 78.5-81.5 32-38
KP Type KP-08R 71.0-75.0 6.0-8.0 Good porosity
NOTE ) Standard values for new KX: Interim values

Secondary Dispersants

Table of Secondary Dispersants
Grade Saponification Degree
(mol % )
Viscosity
(mPas, 4 % )
Product form
L Type LL-810 45.0-51.0 *7.0-10.0 powder(Non water soluble type)
LL-920 30.0-38.0 *9.0-13.0 powder(Non water soluble type)
LL-940 34.0-41.0 *20.0-28.0 powder(Non water soluble type)
LW-100 39.0-46.0 **500-2500 35~38 % aq.solution
LW-200 46.0-53.0 **500-2000 39~41 % aq.solution
*10.0 % Methanol-Water solution(blend ratio:Methanol/Water=1/1) at 25℃ measuered by Hoeppler visocometer.
**40.0 % aq.solution at 25℃ measuered by B-type visocometer.

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