MANUFACTURING PROCESS OF PVCBy Rajat Agarwal

Presented to: Dr. A.N. Sawarkar

INTRODUCTION Polyvinyl chloride is third largest and most

versatile of all thermoplastics. Global production and consumption of Polyvinyl

Chloride PVC in 2010 was approx. 34 million metric tons.

Polyvinyl chloride (PVC) was first manufactured in Germany in 1931 as a robust and lightweight new plastic.

Manufacturing of polyvinyl chloride (PVC) in India started 60 years ago with the country’s first PVC plant set up in Mumbai in 1951

The plant operated by Calico had a capacity of 6000 mt/year.

At present, the Indian PVC industry boasts of a production capacity of 1.3 million mt/year.

In India the total PVC capacity is expected to reach 1635 KTA by 2016-17.

Reliance Industries Ltd has planned capacity expansion to 735 KTA by 2016-17 followed by Finolex at 270 KTA, Chemplast 250 KTA, DCW90 KTA and Shriram70 KTA.

WHAT IS PVC ? PVC is a thermoplastic made of 57% chlorine and

43% hydrocarbon. With the addition of plasticizers, fillers,

reinforcements, lubricants and stabilizer, PVC may be formulated into flexible, rigid, elastomer or foamed compound.

PVC has outstanding combination of durability, stability, flame retardancy, heat-electrical insulation properties, recyclability, excellent long term weather ability and lower price.

PVC comes in two basic forms: rigid and flexible.

PROPERTIES OF PVC Weathering stability. PVC is resistant to aggressive

environmental factors is therefore the material of choice for roofing.

Versatility. PVC can be flexible or rigid. Fire protection. PVC is a material resistant to ignition due

to its chlorine content. Longevity. PVC products can last up to 100 years and even

more. Hygiene. PVC is the material of choice for medical

applications, particularly blood and plasma storage containers.

Barrier properties. PVC can be made impervious to liquids, vapors and gases.

Recyclability. PVC is very recyclable, more so than many other plastics.

Economical efficiency. PVC is the cheapest of large-tonnage polymers providing many products with the best quality-price ratio.

PROPERTIES (CONTD…)

Property Rigid PVC Flexible PVC

Density(g/cm3) 1.3-1.45 1.1-1.35

Thermal Conductivity[W/(m.K)]

0.14-0.28 0.14-0.17

Yield Strength[psi] 4500-8700 1450-3600

Young’s Modulus[psi] 490,00

Comprssion Strength 9500

Resistivity 1016 1012-1015

#source: http://en.wikipedia.org/wiki/Polyvinyl_chloride

APPLICATIONS AND USES

Pipes Clothing and Furniture Plasticizers Flooring Healthcare

Source: http://www.lenntech.com/polyvinyl-chloride-pvc.htm

MANUFACTURE PROCESS

The suspension polymerization process is most widely used process to manufacture PVC.

Manufacturing polyvinyl chloride (PVC) is a three-step process. Producing ethylene dichloride (EDC) Producing vinyl chloride monomer(VCM) Manufacturing polyvinyl chloride (PVC)

http://www.pvc.org/upload/images/Chart_02WEB_imagelarge.jpg

PRODUCING ETHYLENE DICHLORIDE

Chlorine is extracted from sea salt via electrolysis.

Ethylene is derived from hydrocarbon raw materials.

These are reacted to produce ethylene dichloride (1,2-dichloroethane).

C2H4 + Cl2  C2H4Cl2ethylene + chlorine = ethylene dichloride

#source: http://guichon-valves.com/wp-content/uploads/dichlorethane-process.jpg

PRODUCING VINYL CHLORIDE MONOMER

The ethylene dichloride is then decomposed by heating in a high temperature furnace or reactor.C2H4Cl2  C2H3Cl + HClethylene dichloride = vinyl chloride monomer + hydrogen chloride

The hydrogen chloride is reacted with more ethylene in the presence of oxygen (oxychlorination). This produces further ethylene dichloride.

The resultant ethylene dichloride is decomposed according to the above equation, and the hydrogen chloride is again returned for oxychlorination.

2HCl + C2H4 + ½ O2 C2H4Cl2 + H2O C2H3Cl + HCl + H2O

The overall reaction can be shown by adding together the above equations:2C2H4 + Cl2 + ½ O2  2C2H3Cl +H2Oethylene + chlorine + oxygen = VCM + water

#source: http://www.asc.co.id/uplimg/Image/edc.jpg

MANUFACTURING POLYVINYL CHLORIDE PVC is made using a process called addition

polymerisation. This reaction opens the double bonds in the vinyl

chloride monomer (VCM) allowing neighbouring molecules to join together creating long chain molecules.

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There are four polymerization routes for the manufacture of PVC.

Suspension Polymerization

Emulsion Polymerization

Bulk or Mass Polymerization

Solution Polymerization

SUSPENSION POLYMERIZATION

Vinyl chloride is dispersed into very fine droplets by vigorous stirring in water.

Protective colloids like polyvinyl, are added to prevent coalescing of the droplets.

Vinyl-soluble free radical initiators like lauryl are added and polymerization occurs around 50oC.

The polymer is centrifuged from the reaction mixture, washed, and dried.

Applications include injection molding and extrusion (film, tubes).

EMULSION POLYMERIZATION

Vinyl chloride is emulsified in water by adding surfactants and emulsifiers with vigorous stirring

Water soluble initiators like persulfates are used for polymerization.

Purification and drying of the resulting polymer results in a material that is more expensive than a resin produced by suspension polymerization.

However, the polymer in the emulsified state (also known as a plasticol) also can be used.

Examination and surgical gloves use plasticols for their manufacture.

BULK POLYMERIZATION Bulk polymerization is a two-stage process. In the first stage, pure vinyl chloride monomer is

polymerized up to 10% conversion using monomer-soluble free radical initiators.

In the second stage, more monomer is added and the mixture is polymerized with up to 80-85% yield. The excess monomer is stripped off using a vacuum and dried.

PVC obtained from this process is pure, crystal clear, with a narrow particle size distribution. Applications include blow molded bottles.

SOLUTION POLYMERIZATION In solution polymerization, vinyl chloride is

dissolved in organic solvents and polymerized with an organic soluble initiator.

The polymer precipitates from the solution is filtered, washed, and dried.

This process is used to make specialty copolymers with vinyl acetate.

ADDITIVES USED

Additive Properties Achieved

Anti-oxidants & other stabilizers

Slow down the rate at which the polymer will be degraded by oxygen, heat, visible light or UV radiation

Compatibilizers Enable PVC to be mixed with other plastics and helps plastic recycling

Flame retardants Reduce flammability of plastic

Pigments To color the plastic

Plasticizers To produce flexible and manageable plastic

Impact modifiers To absorb shock without damage

Fillers Inexpensive, inert materials that simply add bulk to the plastic

DISADVANTAGES OF PVC

Sensitive to UV and oxidative degradation Limited thermal capability Thermal decomposition evolves HCI Higher density than many plastics

REFERENCES Vinny R. Sastri, Plastics in Medical Devices, Second

Edition, Applied Science Publishers, 2014, Pages 73-120

http://cpmaindia.com/pvc_about.php http://nptel.ac.in/courses/103107082/module8/

lecture3/lecture3.pdf Thornton Joe, “Environmental Impacts of Polyvinyl

Chloride (PVC) Building Materials” http://www.pvc.org/ http://www.vinyl.org.au/pvc-safe-manufacturing/

manufacturing-process http://www.lenntech.com/polyvinyl-chloride-pvc.htm http://en.wikipedia.org/wiki/Polyvinyl_chloride