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HPMC for PVC Making

Mellutel-YT50 controls the particle size and their distribution, influences the porosity and defines the bulk weight of PVC. The porosity of the polymer particles is strongly linked to the property to adsorb additives like e.g. plasticizers or stabilizers. Thereby, the properties of the polymer during processing and of the final product can be controlled.
Ultra low viscous Mellutel-YT50 is the most suitable product for PVC manufacturing processes. Methoxy and hydroxypropyl substitution levels and the viscosity determine the performance characteristics as a PVC suspending agent. Besides this, the particle size of Mellutel-YT50 is specially designed to dissolve perfectly for a smooth PVC polymerization process.

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Product Details

Hydroxypropyl Methyl Cellulose products have the maximum consumption in the area of suspension polymerization of vinyl chloride in China. In the suspension polymerization of vinyl chloride, the dispersed system has a direct impact on the product, PVC resin, and on the quality of its processing and products. Hydroxypropyl Methyl Cellulose helps to improve the thermal stability of resin and control the particle size distribution(in other words, adjust PVC density), and its amount accounts for 0.025% -0.03% of PVC production. PVC resin made from high quality Hydroxypropyl Methyl Cellulose not only can ensure the performance line with international standards, but also can have good apparent physical properties, excellent particle properties and excellent melting rheological behavior.

Structural formula

Hydroxypropyl Methylcellulose for PVC

(n～2)/2

OR=-OH、-OCH3、-[OCH2CH(CH3)]nOH or-[OCH2CH(CH3)]OCH3

Specification

Type	60YT	65YT	75YT
Item	HPMC	HPMC	HPMC
Methoxy %	28.0～30.0	27.0～30.0	19.0～24.0
Hydroxypropyl %	7.0～12.0	4.0～7.5	4.0～12.0
Gel temperature ℃	58.0～64.0	62.0～68.0	70.0～90.0
Viscosity mPa.s	50		100
pH			5.0～8.5
Loss on drying		%	≤4.5
Burning residue		%	＜1.0
Whiteness		%	≥80
Transmittance		%	≥90
Bulk density		g/L	400～500

Applied to PVC features

1. during suspension polymerization, reduce the interfacial tension between vinyl chloride monomer (VCM) and water, and help VCM to be evenly and stably dispersed in the aqueous medium.

2. prevent the coalescence of VCM droplets at the initial stage of polymerization.

3. prevent coalescence between polymer particles in the later stage of the polymerization process.

4. in the suspension polymerization system, it plays a dual role of dispersion and stability protection.

5. with the increase of HPMC viscosity and the decrease of hydroxypropyl content, the interfacial tension increases, the dispersion ability decreases, the glue retention ability increases, the average particle size of PVC resin increases, the resin porosity decreases, and the apparent density increases.