Polyester Tyre Cord Application in Bicycle Tyre S P Pandey Sr. Vice President (Technical) Ralson (India) Limited

Introduction The main objective of this presentation is to replace Cotton fabric by Polyester fabric as casing material in cycle tyre manufacturing with Monoband building machine at comparative cost and better performance Polyester tyre cord is more popular in PCR Tyre due to its known advantages. We have extended its application to Cycle tyre as Re-enforcing material. Bicycle tyres are manufactured mainly with Cotton & Nylon 6 fabric as casing material. Cotton tyre is still popular in India due to cost effectiveness. But there is inconsistency in Quality of Cotton Yarn. In between Cotton and Nylon, Polyester is a good candidate to be used as casing material, Which has added advantage over cotton yarn.

Advantages of Polyester Cord Lighter Weight Cheaper to Nylon Stronger Casing Does not exhibit Flat spotting Better Performance than Cotton Reduced deformation/ Growth in service Excellent Dimensional Stability High productivity due to high MP (260⁰C) (may be used at elevated temperature)

Chemical Structure (C10H8O4)n PET Polyester used, as casing material for tyre is commonly referred to Polyethylene Terephthalate (PET). It contains Ester functional group in their main chain. PET (C10H8O4)n

Physical Properties SR.NO PARAMETER UNIT COTTON YARN 2/2/14 NYLON 840 / D-1 POLYESTER 1000 D/1 1 Breaking Load Kg (Min) 2.5 5.0 7.5 2 Elongation @ Break % (Min) 10 19 13 3 TEX Gms/km 190-200 - 4 Twist Turn/Inch 12 - 14 5 C/V Twist (Coefficient of Variation) % (Max) 6 Moisture 1.0 0.8 7 Thickness (mm) 0.50-0.60 0.33-0.37 0.25 -0.35 8 Denier (Dipped) Gm/Km 900 - 960 1075 - 1125 9 E.P.I Nos 23 20 Hot Air Shrinkage 3.5 2.0 11 Dip Pick Up %(Min) 4.5 3.5 - 4.5 12 Stiffness N/10 Cord 3 – 4 Tread To Ply Adhesion Kg/Inch (Min) 4.0 16 15 14 Ply To Ply Adhesion No Separation

Typical Characteristics of Dipped Cord Nylon 6 Polyester Cotton (Un Dipped) Thermal Shrinkage % <4.5 <1.7 - Dip Pick Up % Min 4.5 3.5 – 4.5 H Adhesion Force (N) 91 72 45

Comparative Consumption Size - 28x1.1/2 Sr. No Cotton/Tyre (gm) Nylon/Tyre Polyester/Tyre 1 79 38 41

WHEEL ENDURANCE TEST:- As per BIS Standard (IS-2414 – 2005)- Size – 28x1.1/2 Stage Load ( kg) No. of Hours (Min) Inflation Pressure (P.S.I) Actual Hours Running (Avg) Cotton Nylon Polyester 1 86 7 60 48 100 57 2 93 16 3 24 Total 47

WHEEL ENDURANCE TEST:- As per BIS Standard all Cycle tyre should run minimum 47 hours at above load irrespective of Cotton , Nylon or Polyester

WHEEL ENDURANCE TEST:- At Constant Load (Clit Type Machine) Hours Running Cotton Nylon Polyester 70 kg load @ 24 km / hours speed 10-12 Hours 75-80 Hours 18 – 20 Hours Zigzag Type Endurance Machine

Conclusion Till recent past Polyester fabric was being extensively used in PCR tyre as casing material. Now Polyester is being used as casing material replacing Cotton in bicycles tyre to provide better product to user. Polyester tyre provides about 1.5 times more life than cotton tyres. Small manufacturer can also afford to use polyester and make tyre on monoband machine. Hot air shrinkage and Cord Stiffness are important for better process control.

Conclusion Processing may be cheaper (No Creel and combing operation needed). Drive Comfort– Due to lighter weight (Low Rolling Resistance). This is an innovative approach to introduce Polyester tyre cord in Bicycle tyre range in India. Which is well accepted in the market. Polyester tyre is better alternative to cotton tyres.

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