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High Tensile Bags
Introduction
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High Tensile bags/film have improved strength properties compared to standard polybags/polythene film at a given thickness therefore saves material and cost.
High tensile bags/film are also known as 'HT' or 'high strength' bags/film.
This bags are highly popular in meat/food packaging industry. HT bags are ideal where extra bag strength or thickness reduction is required.
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How it is made?
High tensile (HT) bags are generally made using blend of two or more polythene to achieve desired physical properties.
Single-layer(mono)'HT' films would be a blend of low and medium density polythene. However, 'HT' film is also made using co-extruded technology.
Major UK suppliers:
Product specification
Common materials used for 'High Tensile'(HT) bags:
- Low density polythene (LDPE)
- Linear low density polythene (LLDPE)
- Medium density polythene (MDPE)
- Recycled polythene
Available Thickness:
80 Gauge(20microns) to 250 Gauge(62.5microns)
Tolerances:
Normally, 'High Tensile(HT) bags' in Great Britain should follow widely accepted industrial standards according to British Standard - see BS7344, 1990
- Width: Plus or minus 3mm (0.125") or 2% whichever is greater
- Length: Plus or minus 6mm (0.25") or 2% whichever is greater
- Gauge: Plus or minus 10%
Standards for 'High Tensile(HT) bags' to use for food contact and medical application:
- Food Contact To use High Tensile(HT) bags inside European Union, in contact
with food should comply with the relevant legislation on food contact including
Great Britain.
- Great Britain: Statutory Instrument, 1998 No. 1376 and BPF-BIBRA (1995), Polymer Specification 4, Polyethylene
- EU: Commission Directive 90/128/EEC, 92/39/EEC, 93/9/EEC, 95/3/EEC and 96/11/EC, Section A.
- Example of a company comply with food contact: Polybags Limited
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Medical use Similarly, to use High Tensile(HT) bags inside European Union,
to produce containers for preparations for medico-pharmaceutical purposes
should comply with the following regulation:
- European Pharmacopoeia - Monograph 3.1.3 "Polyolefin's" for medico-pharmaceutical purposes.
- The final responsibility for the decision of whether a material is fit for a particular application lies with the pharmaceutical firm.
- Example of a company comply with medical use: Polybags Limited
Options for High tensile(HT) bags
Material
- Low density polythene (LDPE)
- Linear low density polythene (LLDPE)
- Medium density polythene (MDPE)
- Coextruded
Appearance
- Light/Tint coloured
- Opaque coloured
- Clear
Plain or printed 'High Tensile(HT) bags'
- Plain
- Printed in 1 colour
- Printed in 2 colour
Variety of 'High Tensile'
- Individual HT Bags
- Block headed with hanging holes for easy tear off - HT bags
- HT bags perforated on roll
- Single wound sheeting
- Centerfold Sheeting
- Gussetted bags
- Layflat tubing
Common areas of application for High tensile bags or film
- Any packaging where you need strength
- Meat packaging
- Food packaging
- Heavy duty shipping sacks
- Builders roll
- Sanitary packaging
Advanced features of High
tensile strength (HT) film
- Extra strength yet lightweight - Very high tensile strength up to 35MPa (up
to 50% stronger than standard polythene film of the same thickness)
- Food use approved
- Greater flexibility and improved toughness
- Good tear/puncture resistance
- Lower cost (thinner film but tougher performance saving both material and cost)
- Films are easy opening, non blocking films making them quick to open ready for filling (saves time)
- Recyclable
Definition of terms used in High tensile(HT) bags or film:
- Tensile strength:- The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before the
material breaks. It is measured in MPa (mega Pascal)
- Toughness:- It is the resistance of a material to fracture or break
- Impact strength:- Energy required to fracture a specimen subjected to shock loading, as in Impact test.
- Puncture resistance:- Extent to which a material is able to withstand the action of a sharp object without perforation.
Common sizes
News - Polybags launches High Tensile film
recent environmental initiatives
- New fully degradable polyfilm grade launched March 2006
- New external Polymer Silos operational December 2005 to store and transfer different polymer grades more economically and without need for pallets or baling sacks
- New down gauging films launched Autumn 2005 [‘HT’ and ‘High
Melt’ grades] to enable identical film strength but at thinner gauges saving customers both material and cost
- We moved away from Company Car Scheme Incentives in Summer 2004
- £45,000 upgrade of Recycling Capabilities in spring 2004 to enable production of 200kg/hr of reprocessed polymer
- Major electrical upgrade in 2003 and installation of flow regulator to smooth electrical usage
Reference: http://www.polybags.co.uk/index.htm?main=environ.htm
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