pvc calender film process

Teaching publicationsTeaching publications

MTT 655 Polymer ProcessingMTT 655 Polymer Processing

: : Calendering: Design and product controlCalendering: Design and product control

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Presentation contents

Principle of calenderingMaterialsProcessing of calenderingProductsAdvantages of calendering process Estimation of output rates and pressure

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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CalenderingCalendering

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Principle of calendering

Consists rollers, Sheet or film formSimple process, Continuous processMinimum thickness of 0.05mm.L/D ratio between 2 to 3; length (L) and diameter (D)(Rollers speeds 10-200 m/min , length 0.5-2.5m, diameter 0.4-0.9m)

Adjusted by heating and cooling systemsUsually the compound mixture of the polymer and filler and/or additive using other mixers (two roll mill, internal mixers and extruders)

Product: shower curtaining, tarpaulins, table cloths, wall covering, rainwear, credit cards, conveyor belt, floorcovering, tyre, waterproofing

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Materials

Poly (vinyl chloride); PVC(reason lies on degradation calendering processing has a relatively shorter residence time)

Polyethylene; PE, Polypropylene; PP(more used in the sheet and film extrusion)

PURubber (carcass coating)

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Calendering MachinesCalendering Machines

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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http://tpe-u.com/tpu/emea/en/processing/special_processes/calendering/Calendering.html

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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CalenderingCalendering processprocess

I-shape

•ชุดลูกรีดไมตองทําหนาที่หลอมเหลวพลาสติก

•ทําหนาที่ปรบัขนาดความหนาของผลิตภัณฑ

•นิยมใชในอุตสาหกรรมพลาสติกในปจจุบัน

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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CalenderingCalendering processprocess

Vertical L-shape

•ผลิตภัณฑแผน PVC แบบแข็ง

•โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว

พลาสติก

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Calendering processCalendering process

F-shape

•ผลิตภัณฑ PVC แบบออน

•โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว

พลาสติก

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Calendering processCalendering process

Z-shape

• ใชในการเคลอืบพลาสติกลงบน แผนผาหรอืเสนดาย

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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PVC Calendering plant

D.H. Morton –Jones, Polymer Processing, CHAPMAN AND HALL

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Factors processing

Roller temperaturePressure of rollerGap sizeRotating speed of the rollersViscosity of the polymer

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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ProductsProducts

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MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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The advantages of calendering

Higher output ratesLess chance of thermal degradationMuch easies to operateLower machine and maintenance costs

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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The disadvantages of calendering

Difficult of control thicknessLimited only to materials in the rubbery stateNo other product (pattern sheet and film) Difficult to control processing temperaturePremixing and compounding are required

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Estimation of output rates and Pressure in calendering

Control properties of the productBehavior of flow

Assumptions- The melt is incompressible- The flow between the rollers is isothermal and laminar- There is no slip between the rollers and the polymer- The size of the rollers is the same

- The rotating speed of the rollers is the same

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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The schematic of flow along the nip in a calender

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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V = 2πRN

Q = HWV

Pmax = 16ηvd3

RH0

V = velocity of the sheetQ = total output rate P = maximum pressureR = radius of the rollers (m)N = rotating speed of the roller (rpm) H0 = size of the nip gapH = thickness of the sheetW = width of the sheet (m)d = distance nip gap to sheet (m)

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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ExampleIn PVC sheet manufacture by calendering, estimate the thickness of the sheet and the maximum pressure developed on the nip of rollers. Roller diameter 50 cm and width 700 cm. The rotating speed of the rollers is 20 rpm. The feed rate of the PVC compound having a viscosity of 104 Ns.m-2

is 0.45x10-3 m.s.-1 The nip gap is 0.2 mm. The PVC compound has a viscosity of 104 Ns.m-2 . The d value is 30 mm.

SolThe velocity of the sheet is determined byV = 2πRN =2X3.14X0.25X20=31.4 m.min-1

Therefore the thickness is:H = Q = 0.45X10-3X60 = 0.001 m

WV 0.70x31.4And the maximum pressure is :Pmax = 16ηVd3 = 16x104x(31.4x60)x(0.03)3 = 1.63x108 N.m-2

RH0 0.25X0.0002

MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala

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Thank youThank you