QUALITY ISSUES RELATED TO SHEET PROCESSING

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Allan Lawson
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1 QUALITY ISSUES RELATED TO SHEET PROCESSING S. Mohanachandran Nair Director Dept of Processing & Product Development Rubber Board India Type wise Production of Natural Rubber (World Scenario- 2010) Country Total Production ( 000 tonnes) RSS (%) Latex (%) Block Rubber (%) Others (%) Thailand Indonesia Malaysia INDIA Vietnam WORLD

2 Type wise Production of Natural Rubber (Indian Scenario ) Type Production (MT) (%) RSS Block Rubber Latex Concentrate (drc) Others Total Type wise Consumption of Natural Rubber (Indian Scenario ) Type Consumption (MT) (%) RSS Block Rubber Latex Concentrate (drc) Others Total

commonly used in small holdings and small estates.

3 NR in Sheet form is the oldest and most popular type. The process of making sheet rubber is relatively simple and commonly used in small holdings and small estates. Sheet Rubber-Types RSS ISNR 3L RSS (Ribbed Smoked Sheet) Air dried sheet 3

4 Ribbed pattern imprints into the sheet to increase the surface area to enhance evaporation rate. Smoking is mainly to prevent subsequent spoiling by microbes. Smoking done at controlled timings and temperatures (40-65º C) Grades RSS classified into 6 major grades Grades Products Equivalent TSR RSS 1 X RSS 1 Superior quality extruded items ISNR 5 RSS 2 Extruded items ISNR 5 ISNR 10 RSS 3 RSS 4 RSS 5 Tire, Conveyor belt etc ISNR 10 ISNR 20 Moulded items low priced ISNR 50 4

5 Grading Depends on Purity Elasticity Color General Specifications The rubber must be dry, firm, free of blisters, mould and foreign matter. Under-cured, opaque, oxidized spots or streaks, melted sheets are not graded. 5

6 Comparison of Physical and Chemical Properties of Block Rubber & Sheet Rubber Characteristic ISNR 20 (typical) RSS 4 (typical) Dirt content, % by mass Volatile matter, % by mass Ash content, % by mass Nitrogen content, % by mass Initial Plasticity (Po) Plasticity Retention Index (PRI) Common defects in RSS Foreign matter Inadequate sieving Pin head bubbles Gas forming bacteria and incomplete coagulation Discoloration - Enzymic action Rust (Resinous matter) Delayed drying Mould growth Inadequate drying and humidity Tackiness Excess acid Blisters Excess drying temperature Rigid sheet Insufficient dilution 6

7 General defects Rigid Sheet ISNR 3L Fungus Bubbles ISNR 50 Correcting defects 7

8 Ideally dried sheet RSS grades depend on Visual Inspection leading to: High probability of inconsistency in grading Normal Thickness of sheet is 2.5 to 3.5 mm. Weight varies from 500 gm to 1300 gm. 8

Packing 50 kg ISNR 3L Often overlooked, but critically important Packed in bundles of 25 kg,35 kg,50 kg and 111.

9 Packing 50 kg ISNR 3L Often overlooked, but critically important Packed in bundles of 25 kg,35 kg,50 kg and kg International bale packing done by shrink wrapping machine to 0.14 cum size weighing kg Why bale coating? Prevent stickiness of bales Prevent fungus formation To stencil grade mark and supplier code 9

10 As per International Green Book (International Standards for Quality & Packing of Natural Rubber Grades, Section - 7), all sheets including wrapper sheets should be equal or higher grade. The permissible limit of bale coating solids is 450 gm for kg or 200 gm for 50 kg bundle. Over coating on bales 10

related health hazards Doping dust damages electronic equipments

11 Over coated bale Adverse ffects of bale coating Excess ash content adversely affecting compounded physical properties Air pollution and related health hazards Doping dust damages electronic equipments Camouflaging inferior sheets with exces doping Manipulation in weight 11

Advantages of Polythene packing LDPE of melting point below 110 o C is consumed in production process Zero wastage Environment friendly with a cost advantage Reduce chances for manipulation in weight

12 Advantages of Polythene packing LDPE of melting point below 110 o C is consumed in production process Zero wastage Environment friendly with a cost advantage Reduce chances for manipulation in weight Polythene stretch wrapping gives better compaction Identification of suppliers and grades is easier by printing supplier and color code for grades Prevents absorption of moisture RSS packed in LDPE bags 12

13 Wrapping in stretch film Thank You for the Attention 13

Circular no.: MCX/WHL/320/2018 August 17, 2018

Circular no.: MCX/WHL/320/2018 August 17, 2018 Procedure for dealing with Rubber at Exchange Accredited Warehouses In terms of provisions of the Rules, Byelaws and Business rules of the Exchange, the Members