wel come pvc pipe extrusion training program ( 13 jan, 2010) g.k.saxena

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WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

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Page 1: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WEL COME

• PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010)

G.K.SAXENA

Page 2: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC RESIN

Page 3: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TOPICS COVEREDTOPICS COVERED

1. Introduction, Historical review.

2. Manufacturing of PVC.

3. Types of PVC.

4. Resin properties & its effect on end use of performance.

5. PVC compounding.

6. Types of Extruder & processing technique.

7. PVC pipe manufacturing process.

8. Miscellaneous.

Page 4: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Overview about Plastics

Thermoplastics-

On heating gets softened and on cooling gets hardened, can be recycled. e.g.- PVC,PP,PE,PS,PAN, PMMA etc.

Thermosetting-

On application of heat they sets, can not be recycled.e.g- MF Resin, UF Resin, PF resin etc.

Page 5: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

IT IS VERSATILE

Page 6: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

• Processing technique for thermoplastic

• Extrusion process• Injection molding process• Rotational molding process• Calendaring process• Blow molding process• Thermoforming process• Reaction injection molding

For thermosetting material• Compression molding• Transfer molding

Page 7: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

HISTORICAL REVIEW OF PVC PIPES

Page 8: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

ADVANTAGES OF PVC PIPES1. Corrosion Resistance.

2. Maintenance free.

3. Easier to install.

4. Light weight.

5. Easy joints technique.

6. Variety of joining technique.

7. Low overall cost an installation.

8. Resistance to chemical.

9. Non toxic.

10. Biological resistance.

11. Abrasion resistance.

12. Different color choice available.

13. Energy saving.

14. Environmental friendly.

15. Recyclable.

16. Fire resistance.

Page 9: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TYPES OF PVC PIPES

1. Agriculture pipes. 9. Threaded pipes.

2. Plumbing pipes. 10. Slotted pipes.

3. Plain pipes. 11. Screen pipes

4. General purpose pipes. 12. Casing pipes.

5. Socketed pipes. 13. Foam core pipes.

6. Corrugated pipes. 14. PVC flexible hoses.

7. Conduit pipes. 15. PVC breaded hoses.

8. Ducting pipes. 16. Flat hoses.

Page 10: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

IT SAVES RESOURCES AND ENERGY

Page 11: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA
Page 12: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA
Page 13: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Monomer

Cl

C

C

H

H

H

Page 14: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

STRUCTURE OF PVC

1. PVC monomer.

2. PVC polymer.The macromolecule polyvinyl chloride (poly = many) is built from very many molecules of the monomer vinyl chloride.

All these monomers are combined to PVC.

These macromolecules are three-dimensional. They look like a knot of wool.

Page 15: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Polymer

Page 16: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

POLYMERISATION OF VINYL CHLORIDEVinyl Chloride Monomer ( VCM )

Vinyl chloride ( A gas boiling at -13.4 Deg.C ) is the monomer. This VCM used to manufactured PVC.

CH2=CH2+Cl2 30 - 50

o C CH2-CH2

Cl Cl

Ethylene Fe-Chloride Ethylene dichloride

( EDC )

CH2 - CH2 Cracking CH2=CH + HCL

Cl Cl 300-600oC (20 sec) Cl

40-60% conversion Vinyl chloride.

[ OXYCHLORINATION ]

Finally divided

CuII Chloride

2CH2=CH2+4HCL+O2 2CH2-CH2+H2O

Cl Cl

Page 17: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Types Of Polymerisation

PVC resin today is manufactured primarily by three processes. The following are the processes.

Suspension polymerisation.Bulk or mass polymerisation.Emulsion polymerisation.

Suspension polymerization produces about 85% world's PVC.

Page 18: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Types Of Pvc

A] Rigid PVC. ( RPVC / upvc )

Rigid PVC pipes, window profile,

B] Flexible PVC.Flexible garden hoses,films

C] CPVC

Plumbing, Fire sprinkler & Building products.

Page 19: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Resin Properties & Its Effect On Resin Properties & Its Effect On End Use PerformanceEnd Use Performance

The performance of a PVC compound depends on following properties of the polymer.1. K-value.2. Apparent bulk density [abd]3. Powder flow time.4. Average particle size & particle size distribution.5. Porosity.6. Fish eyes.7. Dark particles.8. Heat loss.9. Residual vcm.10. Electrical conductivity.11. PVC resin specifications for PVC pipe.

Page 20: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC RESIN SPECIFICATION FOR PVC PIPE

.SR NO PROPERTIES VALUE UNIT

1 Apparent Density 0.49 gm/cc

2 Appearance White Powder ----

3 Inherent Viscosity 0.91 -- 0.92 ----

4 K-Value ( 0.5 gm/100ml 65 -- 68 ----

in cyclohexanone at 25oC)

5 Particl size -- 40 mesh [min.] 99.8 %

Particl size -- 200 mesh [max.] 3 %

6 Volatile content 0.3 % max.

7 Density 1.4 gm/ml

8 Relative viscosity 2.2 ---

9 Ash content < 0.1 %

10 Residual monomer 1 max ppm

11 Flowability < 28 sec.

12 Heating Loss 0.1 %

13 Thermal Stability 50 minute

14 Porosity 0.22 -- 0.32 ml/gm

15 Medium Diameter. 100 - 120 micron

16 Degree of Polymerisation. 1050 nos.

Page 21: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TYPES OF EXTRUDERS

• Single screw extruder.

• Twin screw extruder

a] Single line.

b] Twin line.

• Co extrusion.

Page 22: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC RESIN

ADDITIVES

MIXING1150 C EXTRUDER COOLING HAUL OFF PIPE SAW

PRINTINGSOCKETINGSLOTTING

THREADINGPACKING

TO BSR

REWORK

TO BSR

PROCESS FLOW CHART

Page 23: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WHAT IS CPVC.H H H H

HEAT

C = C + CL2 C = C

H H H CLETHYLENE CHLORINE VINYL CHLORIDE MONOMER

HEAT, PRESSURE

& CATALYST

H H CL H CL H H H HADD CL2

C C C C C C C C C

H CL H CL H H CL H CL

CHLORINATED POLY POLY VINLY CHLORIDEVINLY CHLORIDE ( PVC ) 57 % CHLORINE

( CPVC ) 67 % CHLORINE

( VCM )

Page 24: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

K-value

The average molecule weight of PVC resin is designated as k-value. An increase in k-value leads to an increase in molecular weight, mechanical properties but the melt viscosity becomes higher making processibility more difficult.K-value 67 provides best optimised performance in rigid applications like PVC pipes.

Page 25: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

K-value and Properties.Property PVC K 58 PVC K 67

Processability Fitting Pipe

Fusion Easy Slow

M.F.I. Low High

Impact resistance Good Better

Long term pressure

Resistance Low Good

Page 26: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Apparent Bulk DensityApparent Bulk DensityThe apparent bulk density covers the measurement of flowability of PVC powder, which is useful in predicting its storage, handling and processing characteristics. It is also a measure of fluffiness of the powder and is expressed as weight for unit volume of PVC powder including voids.

Page 27: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Particle SizeParticle size is one of the most obvious ways of distinguishing between different types of PVC resins: dispersion resin, dispersion-blending resin & general-purpose resin.

Particle size of general-purpose resin can affect bulk handling properties and processing characteristics. An excessive amount of fine particles (smaller than 75 microns) can cause dusting and packing problems when adding plasticizer. Coarse particles (425 microns and larger) cause gel problems in processing due to their poorer absorption and fusion characteristics. In general, fineness may indicate following:

1.. The resin will be more difficult to convey.

2.. It will be more susceptible to static charges.

3.. It will increase surface area and thus would require more lubricant.

Page 28: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PorosityPorosity of PVC determines how much and how fast the plasticizers will be absorbed by the resin. A known amount of sample is vacuum impregnated with dioctylphtalate (DOP). Filtration and centrifugation remove the excess dop.

Weight of DOP absorbed

Porosity (ml/gm) = --------------------------------------------

Density of DOP x sample weight

The following properties are affected with the increase in porosity:

Rate of plasticizer absorption : Increase.

Bulk density : Decreases.

Dry blending time : Decreases.

R-VCM content : Decreases.

Page 29: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Heat LossPVC resin contain some volatile mainly in the form of absorbed moisture .A sample of the material to be tested is weighed into a preweighed container and heated in an oven .The loss of weight is calculated as percent heat loss, the non-volatile (solid) residue is calculated as percent total solids.

The following properties are affected with the increase in heat loss:

Porosity : Increases

Processability : Decreases

Product quality : Decreases

Page 30: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Residual Vinyl Chloride Monomer[ VCM ]

A minor quantity of vinyl chloride monomer will always remain absorbed in the resin.

As vinyl chloride monomer is highly toxic, the measurement of residual VCM content in resin is very important.

This residual VCM is measured by head space gas chromatography and is expressed in parts per million parts of resin.

Page 31: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

EXTRUDER

Page 32: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Single Screw Extruder

Page 33: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

FEATURES OF SINGLE SCREW EXTRUDER

• LOWER OUTPUT – MORE COST OF PRODUCTION

• FIXED PRODUCTION – DUE TO OPTIMUM RPM

• OPERATES THROUGH FRICTION – MORE DEGRADATION

• LIMITATIONS OF L / D RATIO – 24 – 32

• MIXING THROUGH BACK PRESSURE & FRICTION - NON HOMOGENITY AND

LIMITATIONS IN QUALITY

• HIGHER RESIDENCE TIME – MORE DEGRADATION & MORE DOSES OF STABILIZER

Page 34: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

Screw Geometry Of A Twin Screw Extruder

Page 35: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TYPE OF TWIN SCREW EXTRUDERS

       TWIN SCREWS CAN BE –

CO-ROTATING OR CONTRA ROTATING.

       THE BARREL AND SCREW CAN BE –

•PARALLEL, •STEPPED, •CONICAL OR•SUPER CONICAL.

       OVER ALL OUTPUT OF TWIN SCREW EXTRUDERS IS MUCH MORE THAN SINGLE SCREW EXTRUDERS.

Page 36: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

BETWEEN FEED ZONE & VACUUM PORT

      THE SCREWS SHOULD BE FILLED COMPLETELY FOR MAXIMUM OUTPUT.

     FAIRLY AGGRESSIVE HEATING IS REQUIRED IN THE FIRST TWO ZONES TO FACILITATE EXTRACTION OF

1. VOLATILES,

2. MOISTURE

3. HCl GAS GENERATED DUE TO DEGRADATION.

DURING VACUUM DEGASSING.

Page 37: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

MIXING & SHEARING

     IN TWIN SCREW EXTRUDERS THE SCREW R.P.M. IS LOW AND HENCE THERE IS LOW SHEAR AT THE BARREL WALL RESULTING IN LOW MIXING.

     HOWEVER GOOD MIXING TAKES PLACE THROUGH

1. THE CLEARANCE BETWEEN FLANKS OF OPPOSING SCREWS, AS WELL AS

2. THE FLIGHT LAND OF ONE SCREW AND THE BOTTOM CHANNEL OF THE OPPOSING SCREW PROMOTE INTERCHANGE OF MATERIAL

BETWEEN SCREWS RESULTING IN GOOD MIXING.

Page 38: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

AT VACUUM PORT

     LOOK AT THE VACUUM PORT WITH A FLASH LIGHT.

     NO DRY POWDER SHOULD BE VISIBLE AT ANY TIME FROM THE VACUUM PORT.

     THE DRY BLEND SHOULD LOOK POWDERY BUT STICKY LIKE WET SAND.

     THE GRAINS MUST STICK TOGETHER BUT SHOULD NOT FUSE. [ GELLATION ]

THE TEMPERATURE OF MATERIALAT VACUUM PORT SHOULD BE AROUND 150 °C.

Page 39: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

ENERGY UTILIZATION

      MECHANICAL ENERGY FROM THE MOTOR IS USED FOR –

   MIXING AND IN TURN IN RAISING THE TEMPERATURE OF THE POLYMER.

THIS IS DESIRABLE, AS DUE TO POOR THERMAL CONDUCTIVITY OF THE POLYMER, HEAT TRANSFER FROM THE BARREL IS NOT SUFFICIENT.

  IF HIGH OUTPUT IS ACHIEVED WITH INSUFFICIENT MECHANICAL ENERGY, QUALITY OF THE PRODUCT MAY BE POOR DUE TO INSUFFICIENT FUSION.

Page 40: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

COMPRESSION

• THE BULK DENSITY OF THE DRY BLEND

ENTERING THE HOPPER IS ABOUT 0.6 g / cc. • THE MELT DENSITY IS ABOUT 1.45 g / cc.

• A CONSIDERABLE AMOUNT OF COMPRESSION MUST TAKE PLACE WITHIN THE EXTRUDER.

   •   THE SCREWS / BARREL MUST PROVIDE

COMPRESSION THROUGH THE DESIGN OF BARREL AS WELL AS DESIGN OF FLIGHTS.

THE EXTRUDER HAS FEED ZONE, COMRESSION ZONE AND METERING ZONE.

Page 41: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PROCESSING IN TWIN SCREW EXTRUDERS

      THE FOCUS IN TWIN SCREW EXTRUSION IS DIVIDED IN FOUR PARTS -

1.   THE DRY BLEND MIXING OPERATION.  

2.   BETWEEN FEED ZONE AND VACUUM PORT. 

3.   BETWEEN VACUUM PORT AND DIE.

4.   WITHIN THE DIE.

       IN PVC PROCESSING WHAT MATTERS IS THETEMPERATURE OF PVC AND NOT THE TEMPERATURE OF ANY PART OF THE EXTRUDER.

Page 42: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

DIE HEAD

Page 43: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

CALIBRATION SYSTEM

Page 44: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

HAUL OFF UNIT

Page 45: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

CUTTING UNITS

Page 46: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

COMPOUNDING

Page 47: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC COMPOUNDING.

PVC RESIN

FOAMINGAGENT

FILLER

LUBRICANTS

STABILISER

IMPACTMODIFIER

PIGMENT

Page 48: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

COMPOUNDING

       PVC CAN NOT BE PROCESSED WITHOUT COMPOUNDING IN ITS ORIGINAL FORM.

 

       A PROCESS OF HOMOGENEOUSLY MODIFYING PVC THROUGH ADDITIVES, TO ACHIVE PROCESSABILITY AND DESIRED PROPERTIES IN THE FINISHED GOODS, IS KNOWN AS COMPOUNDING.

       INTERESTINGLY, THE COMPOUND VARIES FROM MACHINE TO MACHINE, CONDITION OF THE MACHINE, PRIORITIES OF DESIRED PROPERTIES AND THE TYPE AND QUALITY OF ADDITIVES USED.

FORMULATION COPIED FROM A BOOK OR FROM ONE INDUSTRY MAY NOT WORK AT ALL IN OTHER INDUSTRY.

Page 49: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

NECESSITY OF STABILIZATION

• PVC IS THE MOST HEAT SENSETIVE OF THE MAJOR THERMOPLASTIC RESINS. IT DEGRADES BEYOND 80 DEG. C.

• HEATING UNSTABILIZED PVC ABOVE ITS FUSION POINT GIVES RISE TO -

– YELLOWING– FOLLOWED BY BROWN DISCOLOURATION,– EVOLUTION OF HYDROCHLORIC ACID– CROSS LINKING,– CHAIN SCISSION, – ULTIMATE CHARRING TO INFUSIBLE, UNPROCESSABLE,

CORROSIVE BLACK MASS– IRREVERSIBLE ADHESION TO EQUIPMENT SURFACE

Page 50: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

REQUIREMENTS OF COMPOUND

• COMPOUNDER SUPPLIES COMPOUND TO INTERNAL OR EXTERNAL CUSTOMER AS PER THEIR REQIREMENTS

• THESE REQUIREMENTS ARE –

1. DRY BLEND SHOULD BE FREE FLOWING

2. COMPOUND SHOULD BE HOMOGENEOUS AND CONSISTANT FROM BATCH TO BATCH.

3. COMPOUND SHOULD BE PROCESSABLE ON GIVEN EQUIPMENT

4. THE PRODUCT MADE FROM THIS COMPOUND SHOULD PASS IN ALL THE TESTS AS PER AGREED SPECIFICATION.

Page 51: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

ESSENTIAL INGRADIENTS        THERMAL STABILIZER -- TO SUPPRESS DEGRADATION

[LEAD,TIN, Ba-Cd, Ca-Zn] TO EXTEND EXPOSURE TIME        INTERNAL LUBRICANT – TO FACILITATE THE MOVEMENT

BETWEEN POLYMER CHAINS & DECREASE MELT VISCOSITY

       EXTERNAL LUBRICANT – TO REDUCE FRICTION BETWEEN POLYMER AND METAL SURFACE.

       POLYMERIC – TO PROMOTE FUSION, PROCESSING AID TO ALTER MELT RHEOLOGY, TO ENHANCE PROCESSIBILITY

– IMPACT MODIFIER – TO IMPROVE IMPACT STRENGTH AT LOW TEMPERATURE

       PLASTICIZER – TO INCREASE FLEXIBILITY

      EXTENDER FILLER – TO REDUCE COST FUNCTIONAL FILLERS -- TO MODIFY IMPACT, MODULUS,

HARDNESS, H.D.T.,U.V.RESISTANCE DIMENSIONAL STABILITY ETC.

Page 52: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

HEAT STABILISERChoice of stabilizer depends upon :

1. Requirement of processing.

2. End use property.

3. Interacting with formulation components.

4. Meeting specification of various regulatory agencies.

5. Toxicological and environment safety.

Page 53: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TYPES OF HEAT STABILIZER

1. Lead stabilizer.

2. Tin stabilizer.

3. Barium Cadmium.

4. Cadmium zinc.

5. Lead salts and soap.

6. Organic stabilizer [ Non metals ]

Page 54: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

VARIOUS LEAD STABILIZERSNON LUBRICATING

• LEAD OXIDE - PbO – LOW COST - YELLOW IN COLOUR [ 9.5]

• WHITE LEAD – PbCO3. Pb(OH)2 - LIBERATES CO2 AT HIGH TEMP [6.6]

• TBLS - 3PbO.PbSO4.H20 - SAPONIFIES ESTER PLASTICIZERS [6.4]

• B.L.S.S. - COMPLEX - LONG TERM RETENTION EL. PROP [ 5.5]

• DBLPH - 2PbO.C6H4(COO)2Pb - BAD LIGHT STABILITY [4.6]

• DBLP - 2PbO.PbHPO3.1/2 H2O - BEST WEATHERABILITY & EL.PR. [6.1]. WHITE, NON GASSING, NON REACTING

LUBRICATING

• DBLS - 2PbO.(C17H35COO)2Pb - GOOD LUBRICITY [2.0] , 250 DEG.C

• LS - (C17H35COO)2 Pb - GOOD LUBRICITY [1.4] , 110 DEG.C

• LEAD OCTOATE- (C7H16COO)2 Pb-LIQUID, BAD WEATHERABILITY [1.1]

Page 55: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

DISADVANTAGES OF LEAD STABILIZER

• BEING SOLID, THEY HAVE LIMITED COMPATIBILITY

• PIGMENT LIKE CHARACTERISTICS

• CAN NOT BE USED FOR CLEAR APPLICATIONS

• UNABLE TO IMPART LONG TERM INITIAL COLOUR HOLD

• PRONE TO SULFIDE STAINING. THEY DISCOLOUR IN CONTACT WITH H2S OR METAL SULFIDES

• TOXIC

• LEAD OCTOATE IS LIQUID. BUT WHEN USED THE PRODUCT GETS DARKENED ON EXPOSURE TO SOLAR RADIATION

Page 56: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PIGMENT

COLOURED[ RARELY USED ]

BLACK[CARBON BLACK]

ORGANICPIGM ENT

S YNT HE T IC NA T URA L

COLOURED

ANATASE RUT ILE

T iO 2

W HITE

INORGANICPIGM ENT

PIG M ENT

Page 57: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

LUBRICANTS.1. Internal Lubricants :

* It is use as lubricants for transparant products.

* It reduce internal friction.

* It give better wall thickness to product.

* It reduces viscosity.

* Slight effect on fusion time.

* It has negative effect on softening point.

* It is no real effect on sticking of the polymer to metal.

Page 58: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

LUBRICANTS..2. External Lubricants :

* It reduces sticking to metal surface.

* It is not compatible with polymer.

* The fusion time will be made longer.

* It reduces plate out.

* It reduces melt friction.

* It reduces burning of PVC during processing.

Page 59: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

FILLERFiller are added to PVC for giving specific property :

* Improvement of flow behavior of melt in die head.

* Reduces shrinkage.

* Reduces cost of compound.

* Improvement in heat conductivity of PVC.

* To make opaque product.

* Improvement in stiffness.

* Upto 2 -3 phr they add as a processing add and more than this they are filler.

Page 60: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

TYPES OF FILLER1. Calcium carbonate.

a] Activated & Coated.

b] Natural. ( Calcite )

2. Gypsum

3. Talc.

4. Barrite.

5. Calcium Magnesium carbonate.

6. Silicates.

7. Calcium sulfate.

Disadvantages of excess use of filler :

* Long term pressure resistance.- Reduces

* Impact resistance.- Reduces

Page 61: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

IMPACT MODIFIER

Specific application of PVC leads modification of formulation by adding the impact modifier.

Types of Impact modifier

* Chlorinated polyethylene. [ C.P.E. ]

* Ethylene vinyl acetate copolymer. [ E.V.A. ]

* Acrylonitirile butadiene styrene terpolymer.[ A.B.S.]

* Methacrylate butadiene styrene terpolymer.[ M.B.S.]

* Acrylate polymethacrylate copolymer. [ A.C.E. ]

Page 62: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

MIXING

Page 63: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

MIXING• IT IS A COMPLEX PROCESS OF HOMOGENISING - SUSPENSION

OR MASS PVC AND ALL THE INGRADIENTS, SOLID OR LIQUID, BY PREFERENTIAL ABSORPTION, ADSORPTION AND COATING TO GET A CONSISTANT FREE FLOWING COMPOUND.  

• BOTH DISTRIBUTIVE AND DISPERSIVE MIXING TAKES PLACE.

 •       MIXING IS CARRIED OUT IN A COMBINATION OF HOT AND

COLD MIXERS.

•       DRY BLENDING INVOLVES-

1. MIXING OF INGREDIENTS AT HIGH SPEED FOR RIGID PVC

2. MIXING AT LOW SPEED FOLLOWED BY HIGH SPEED FOR PLASTICIZED PVC IN HOT MIXER. THE DRY BLEND IS COOLED IN LOW SPEED COOLER MIXER TO GET FREE FLOWING COMPOUND.

Page 64: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

HOT MIXING

      UNIFORM OPERATION IN THE MIXING BATCHES IS THE KEY TO SUCCESSFUL EXTRUSION.

       MIX ALL THE BATCHES AT SAME TEMPERATURE, TORQUE

AND TIME AND FOLLOW THE SAME SEQUENCE OF ADDITION OF ADDITIVES.

      MORE THE DROP TEMPERATURE, MORE THE BULK DENSITY OF THE DRY BLEND.

     OPTIMUM DROP TEMPERATURE IS 120 °C

Page 65: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WHAT HAPPENS INSIDE HOT MIXER

• WHEN PVC IS CHARGED IN THE HIGH SPEED MIXER ALONG WITH STABILIZER AND OTHER NON MELTING INGREDIENTS FOLLOWING ACTIONS TAKE PLACE –

1. DURING HOT MIXING INGREDIENTS ARE THROWN AGAINST THE WALL OF HOT MIXER.

2. THE TEMPERATURE OF THE PARTICLES RISE DUE TO FRICTION @ 8 –10 DEG. C. PER MINUTE.

3. SOLID GRAINS OF PVC AND OTHER NON MELTING ADDITIVES ARE HOMOGENEOUSLY BLENDED.

4. THE PATH OF THESE PARTICLES CAN BE SEEN AS A SPIRAL AROUND THE CONTAINER AXIS SUPERIMPOSED WITH GRAVITATIONAL FORCE, CREATING A WELL KNOWN VORTEX MOVEMENT IN A FLUIDIZED BED.

Page 66: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WHAT HAPPENS INSIDE HOT MIXER

5. AN ADJUSTABLE BAFFLE PROVIDED IN THE HOT MIXER, BREAKES THIS VORTEX AND DEFLECTS THE MATERIAL TOWARDS THE CENTRE OF THE VORTEX.

6. THUS, MOVEMENT OF MATERIAL TAKES PLACE BOTH IN VERTICAL AS WELL AS HORIZONTAL DIRECTION RESULTING IN EFFECTIVE MIXING.

7. PARTICLES IMPACT EACH OTHER, THE MIXER WALL AS WELL AS THE MIXER BLADES RESULTING IN RISE IN TEMPERATURE.

8. ROUNDING OFF OF IRREGULARLY SHAPED PARTICLES AS WELL AS SURFACE CHANGES OF THE POLYMER TAKES PLACE RESULTING IN INCREASE IN BULK DENSITY.

Page 67: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WHAT HAPPENS INSIDE HOT MIXER

9. AS THE TEMPERATURE RISES, PVC GRAINS BECOME SOFT, PORES

OPEN UP AND LIQUID INGREDIENTS GET ABSORBED.

10. SOFTER ADDITIVES BEGIN TO MELT AND COAT THE PARTICLES.

11. IT IS RECOMMENDED TO ADD EXTERNAL LUBRICANTS 20 DEG.C. BELOW THE DROP TEMPERATURE. THIS WILL PROVIDE MORE FRICTIONAL HEAT AND IMPROVE MIXING QUALITY.

Page 68: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

WHAT HAPPENS INSIDE HOT MIXER

12. MOISTURE PRESENT IN THE INGREDIENTS IS DRIVEN OFF AS THE TEMPERATURE CROSSES 100 DEG.C.

13. IT IS INTERESTING TO NOTE THAT IN CASE OF RIGID PVC, MORE THE MIXING TIME –

A. MORE IS THE COMPOUND TEMPERATUREB. MORE IS THE BULK DENSITYC. MORE IS THE UNIFORMITYD. MORE IS THE OUTPUT IN TWIN SCREW EXTRUDERS FOR PIPES,

PROFILES, SHEETS ETC.

14. WHEN THE DROP TEMPERATURE REACHES, THE HOT MIXED CONTENTS ARE DROPPED IN COLD MIXER EITHER MANUALLY OR AUTOMATICALLY.

Page 69: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

COLD MIXING

     COOL THE BATCH TO SAME TEMPERATURE.

     VARIATION IN THE FINAL TEMPERATURE OF THE DRY BLEND AFFECTS THE LOCATION OF FUSION IN THE EXTRUDER. THE OPTIMUM COMPOUND TEMPERATURE FROM COLD MIXER IS 40 °C.

       TOO MUCH COOLING WILL RESULT IN MOISTURE

CONTENT IN THE DRY BLEND DUE TO CONDENSATION.

    CARBON BLACK HAS A VERY HIGH SURFACE AREA PER UNIT WEIGHT AND HAS AFFINITY FOR GASES AND MOISTURE, WHICH IT ABSORBS LIKE A SPONGE.

Page 70: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

EFFECT OF DRY BLEND TEMPERATURE

       DRY BLEND TEMP. PLAYS A VERY VITAL ROLE. IT SHOULD BE AROUND 40 °C.

       SUPPOSE YOUR DRY BLEND TEMP IS 20 °C MORE. THE TEMPERATURE AT VACUUM PORT WILL RISE TO AROUND 170 °C, INSTEAD OF 150 °C.

        THE TORQUE WILL RISE.

       THE MATERIAL WILL BE FUSED BEFORE VACUUM PORT.          THE PRODUCT WILL HAVE VOIDS DUE TO TRAPPED AIR AND

MOISTURE RESULTING IN POORER IMPACT AND MECHANICAL STRENGTH.

        DUE TO MORE HEAT AND TORQUE IT MAY DEGRADE, FURTHER

RESULTING IN BAD QUALITY.

Page 71: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

BETWEEN VACUUM PORT & ADAPTER      THIS IS THE AREA WHERE PVC SHOULD FUSE.

OPTIMUM FUSION SHOULD BE 60 TO 65 %      IF THE CONSISTENCY AT VACUUM PORT

LOOKS GOOD BUT THE TORQUE IS TOO HIGH, TRY TO INCREASE THE ADAPTER TEMPERATURE BY FEW DEGREES.

      THE ADAPTER IS LIKE A VALVE.

-HIGHER TEMPERATURE OPENS IT UP.

-LOWER TEMPERATURE CLOSES IT.

Page 72: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

LOCATION OF FUSION

     DEPENDING THE SIZE OF THE DIE, WE SHOULD BE ABLE TO CHOOSE THE PLACE OF OPTIMUM FUSION. SOME TIMES THE FUSION CAN TAKE PLACE EVEN IN DIE.

     IF YOU HAVE POOR FUSION AND THE METERING

ZONE TEMPERATURES ARE AT MAXIMUM LIMIT, TRY TO REDUCE ADAPTER TEMP LITTLE BIT.

     THE MELT WILL GET HOTTER AND THE TORQUE WILL RISE AND THEN FALL OFF AGAIN TO A LEVEL JUST ABOVE THE INITIAL LEVEL.

Page 73: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

CHANGES DURING EXTRUSION        ANY CHANGE YOU MAKE, DO IT GENTLY.

       TEMP. INCREASE SHOULD BE AT THE MOST 5 °C. AT A TIME.

       WAIT FOR 20 MINUTES BEFORE YOU MAKE ANOTHER CHANGE.

       ANY CHANGE IN ONE PART OF AN EXTRUDER AFFECTS ALL PARTS OF IT.

         NOTE ALL YOUR CHANGES IN A LOG BOOK.         MAKE SURE THAT THE SAMPLE CHECKED FOR PHYSICAL

PROPERTIES MATCHES CORRECTLY WITH THE CORRESPONDING EXTRUSION CONDITIONS, TO AVOID WRONG CONCLUSIONS.

         IF YOUR INPUTS ARE CONSISTENT, YOU MAY HAVE TO MAKE

MINOR CHANGES, BASED ON THE CONTROL PLAN DATA ON PARAMETERS AND THE TEST RESULTS AVAILABLE.

Page 74: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shooting

Page 75: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingA) The Main motor consumes too much power:

1) Resistance of the die is too high. 2) Heavy damage of screw. 3) The screws are worn by 1mm or more. 4) Screw cooling system cools screw effectively. 5) Less amount of lubricant in compound. 6) Degree of filling of the screw is too high. 7) Last two barrel zone are at too low temp. 8) Wrong alignment of screw.

B) The intake capacity of the screw is too low : 1) Pour ability of compound is too low. 2) Bulk density of compd.is too low. 3) Back word force of air. It pushes back the incoming powder. 4) Incorrect design of intake zone ( Pitch or Channel depth) 5) Intake opening of barrel too small. 6) Air entrapped in PVC powder due to its small particles.

Page 76: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingC) PVC is powdering in the venting zone : 1) Degree of filling of the screw is too low. 2) Degree of fusion in the degassing zone is too low. 3) Air leaking from meeting flanges .

D) The force on the trust bearing is higher than normal : 1) Touching of screw flights. Pour ability of compound is too low. 2) Short length of the cooled section of the screws. 3) Melt temp too high. 4) Effective cooling of screw cool system.

E) Melt temp & die pressure are unstable: 1) The length of cooled section of the screw is too short. 2) Extruder operates at very low melt temp.

F) The melt temp is too high. 1) Use of new screw & barrel. 2) Pressure drop over the die is too high. 3) Mechanical damage of screws. 4) Less amount of lubricant in compd. 5) High barrel temp setting. 6) Low degree of filling of the screws. 7) Effective cooling of screw cool system 8) Short length of the cooled section of the screws. 9) Defective screw cooling system. 10) Screws are worn too much.

Page 77: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shooting

G) Melt temp is low : 1) Lower setting temp of barrel. 2) High degree of filling of the screws. 3) Low pressure drop over the die. 4) High amount of lubricant in the compd. 5) Insufficient mixing elements near screw tips.

H) The outside surface of the pipe is rough: 1) High melt temp. 2) Die is locally too hot.(>210 deg.cent.) 3) Die is locally too cold. 4) Leaking of PVC through meeting flanges & become carbonized. 5) PVC stagnating in somewhere in the die and burns 6) Local damage of die surface. Peel off of chromium . plated layer. 7) Oil leakage into the melt from the tips of the screws results into burning. 8) Less dosage of heat stabilizer in the compd.

I) Plate- out occurs in the die: 1) PVC stagnating in somewhere in the die ( becoz of Rough die surface / Dead spots / too small curvature/ Gaps between

meeting flanges / too steep slopes in the flow line). 2) High melt temp. 3) High moisture in the compd. 4) PVC type used is sensitive for plate-out formation.

Page 78: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingJ) Pressure drop over the die is too high : 1) Die is too cold. 2) Melt temp is too low. 3) Resistance of the die is too high. 4) The force of the screws on thrust bearing is high.

K) The die disturbs the flow of the melt : 1) Malfunctioning of one or more heating elements. 2) PVC is burned in the die. 3) Plate-out occurs in the die. 4) Damage of die. 5) Irregular lubrication of the die surface. 6) One of the spider leg is too cold. 7) The compression ratio of the die is too low. 8) Leakage of oil from the tips of the screw.

L) The diameter of the pipe is too small: 1) The vacuum is lower than normal. 2) Calibration sleeve diameter is small. 3) The o/p of the extruder is higher than normal.

Page 79: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingM) The diameter of the pipe is too large : 1) The o/p of the extruder is lower than normal. 2) The vacuum is higher than normal. 3) Calibration sleeve diameter is large.

N) The pipe is oval : 1) Insufficient cooling of the pipe. 2) Small length of vacuum tank. 3) The vacuum is low. 4) In-proper alignment of supporting rollers.

O) The improper cent ration of the pipe : 1) The homogeneity of the melt is bad. 2) Temp differences in the melt. 3) Sticking of extrudate to the calibration sleeve.

P) The homogeneity of the melt is bad : 1) Temp differences in the melt. 2) Degree of filling of the screws is too low. 3) High temp of last barrel zone /screws. 4) Insufficient mixing capacity of screws. 5) Too large throat piece is used. 6) The flight gaps of the screws are too small.

Page 80: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingQ) The heat reversion of the pipe is too high : 1) The gap of the die land is too large.

2) High friction at the wall of the calibration sleeve. 3) Low melt temp. 4) Orientation of the melt while being cooled down

R) The internal bore of the pipe is too rough : 1) Waviness of the pipe is too high. 2) Die creates melt fracture in the pipe. 3) Screw marks present in the pipe. 4) Low temp of the die. Melt sticks to the wall of die. 5) Ring shaped deformations are present. 6) The extrudate sticks to the calibration sleeve.

S) The waviness of the pipe is too high : 1) High o/p of the extruder. 2) Bad homogeneity of the melt 3) Small compression ratio of the die.

T) The die creates melt fracture in the pipe : 1) Very low melt temp. 2) Rate of elongation in the die is too low. 3) The surface of the die is too cold.

Page 81: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shootingU) Two rough regions are present left & right : This is due to melt stayed longer time near the core of the screws. Its temp is different from that of the rest of the melt. Even possible in degraded melt. Pipe shows attack in MCT near those regions.

V) Screw marks are present in the pipe: Possible when temp of the melt is not uniform. The melt near by wall of the screw flight is warmer than the melt present at the centre of screw channels.

W) Ring – shaped deformations are present: 1) Pipe slips in the tracks of haul-off. 2) Irregular speed of haul-off. 3) Cutter exerts too much force on the pipe. 4) High friction at the wall of the calibration sleeve. 3) More distance between the calibration sleeve and the die.

X) The outside surface of the pipe is rough : 1) Waviness of the pipe is too high. 2) PVC is burned in the die. 3) The extrudate sticks to the calibration sleeve. 4) The extrudate pressed in the gap between the die & the calibration sleeve. 5) The alignment of die and calibration sleeve is not proper. 6) Inner mandrel of the die is longer than outer mandrel. The extrudate can not flow correctly into the calibration sleeve. 7) Calibration sleeve is not functioning properly.

Page 82: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shooting

Y) Whitened region or strips at the outer surface: 1) High friction at the wall of the calibration sleeve. 2) The calibration sleeve is worn. Lubricants accumulate in this regions cause the stripes.

Z) The bottom of the pipe is deformed : Accumulation of lubricants at the bottom of calibration sleeve.

AA) Attack of Methylene chloride all around the pipe: 1) Low melt temp. 2) Low degree of fusion.

AB) The degree of fusion is too low : 1) Low amount of shearing inside the extruder. 2) Low melt temp.

AC) MC attack left & right: Sticking of PVC in the side gaps of the degassing zone .This material degrades & finally enters the sides of the pipe.

AD) The pipe shows porosity : 1) Low vacuum in the degassing zone. 2) More fusion of melt in the degassing zone. 3) Degassing time of melt is too short. 4) The thermal stability of the compd is too low. 5) Sticking of PVC in the side gaps of the degassing zone

Page 83: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Problems

AE) The spider line weld quality is bad : 1) The compression ratio of the die is too small. 2) The compound contains high amount of lubricants.

AF) The gloss of the pipe surface is low : 1) The temp of the die near die the die land is too low. 2) High melt temp. 3) The PVC contents is more.

AG) Small carbonized particles are present in the pipe: 1) The wall of the barrel is polluted with carbonized PVC .Small parts of it enter the melt.. 2) Accumulation of PVC in the vent. of the extruder.

AH) Scratches are present on the surface of the pipe : 1) Plate-out occurs in the die. 2) PVC is burned in the die. 3) The calibration sleeve is polluted. 4) Inner mandrel of the die is longer than outer mandrel. Burned PVC accumulates at the end of the inner mandrel .

AI) The pipe fails in impact test : 1) Scratches present on the surface of the pipe. 2) Low degree of fusion. 3) Small carbonized particles present in the pipe. 4) The pipe contains porosity. 5) One of the additives contains too much large particles.

Page 84: WEL COME PVC PIPE EXTRUSION TRAINING PROGRAM ( 13 JAN, 2010) G.K.SAXENA

PVC Extrusion Trouble shooting

AJ) Pipes fails in pressure test :

1) Scratches are present on the surface of the pipe.

2) Low degree of fusion.

3) Small carbonized particles present in the pipe.

4) The pipe contains porosity.

5) One of the additives contains too much large particles.

6) The spider line weld quality is bad.

AK) The overweight of the pipe is too high :

1) The internal bore of the pipe is too rough.

2) The haul-off speed is too slow.

3) The cent ration of the pipe is not proper.