GB2385823A

GB2385823A - Improvements in or relating to flexible barriers

Info

Publication number: GB2385823A
Application number: GB0303067A
Authority: GB
Inventors: Peter Andrew Hill; Timothy Michael Strawson
Original assignee: BRADBURY GROUP Ltd
Current assignee: BRADBURY GROUP Ltd
Priority date: 2002-02-11
Filing date: 2003-02-11
Publication date: 2003-09-03
Anticipated expiration: 2023-02-11
Also published as: GB0203151D0; GB2385823B; GB0303067D0

Abstract

The invention relates to a barrier material in flexible sheet form including layers selected from one or more of a sheet material formed from ultra high molecular weight polyethylene fibre, a sheet material formed from aramid fibre, and a knitted mesh layer. An aramid fibre layer may be provided with intersecting pockets to accommodate a wire or cable running throughout the sheet to provide additional resistance to cutting. The wire or cable may be contained in a braided aramid fibre cover. Barriers including the barrier material and security enclosures employing the barriers are also described.

Description

Improvements in or relating to Flexible Barriers The present invention relates to barrier materials and especially barrier materials which can be used to prevent or delay unauthorised access to a room, equipment storage area, manufacturing area or other designated space. The materials of the invention are flexible in that they can accommodate a degree of intended deformation but are also mechanically strong to resist mechanical shock. Typical mechanical shocks can include the action of cutting devices, impact from heavy implements or projectiles, or pressure waves from explosions.

In a particularly preferred form of the invention, the barrier material of the invention is incorporated into a suitable framework to form a folding or roller shutter or curtain.

In preferred constructions, the barrier material of the invention comprises a layered construction or laminate of a number of different materials, each material being selected to provide particular properties to the laminate.

Typically, the materials of the invention must be resistant to cutting with a knife or other sharpened implement, or with wire or bolt cutters and, advantageously will be resistant to penetration or puncture by a screwdriver or like implement. If such puncture is possible, the materials of the invention will desirably resist expansion of the hole so created beyond a certain maximum size such as, for example a maximum dimension of 25mm. In this way, further damage to the materials from cutting devices is resisted, since access to the material by these devices is restricted.

In typical constructions, the laminate materials according to the invention will include outer cover materials on the external faces of the laminate. These cover materials are optional and may be provided primarily for aesthetic reasons. As such the cover materials do not need to contribute to the mechanical strength and resistance of the laminate material of the invention. Suitable examples of cover

materials include cotton and other fabrics which may be dyed or printed as desired.

Desirably, the cover materials may be treated with fire retardant materials (or may in themselves be fire retardant).

Particularly preferred laminate materials according to the invention include a layer of material which has high tensile strength and which is resistant to shearing or cutting of the laminate with a knife, side cutters, pliers of the like by virtue of visco-elastic properties which result in an apparent"fusing together"of the material (e. g. of the fibres of the material) on the cutting action. In this way, the cutting action blunts the blade of the knife or other implement. Also, cutting with cutters such as side cutters is not possible in one action. Typical suitable materials are non-woven ultra high molecular weight (uhmw) polyethylene fibre materials such as those available from AlliedSignal Inc or Honeywell Performance Fibers under the trademark"SPECTRA" in the form of a substantially white sheet material. High strength uhmw polyethylene fibre for manufacturing suitable materials is also available from DSM of Holland or Toyobo of Japan under the trade mark Dyneema. Typical laminate materials of this type have a weight in the range of from about 150gm-2 to about 350gem-2 and a thickness of about lmm to 3mm. Particularly preferable materials have a weight of about 250gm -2 and a thickness of about 2mm. Sheet materials produced from

aramid fibres such as Kevlar Tm are also suitable, but less preferred. Another preferred laminate layer of the material according to the invention comprises a"knitted mesh"material which comprises a sheet of interlocked, knitted or interwoven wire. This material is very flexible and lightweight but provides excellent resistance to cutting by either knives or other sharpened implements, or by cutters. This material is also advantageous in hindering any increase in the size of holes made in other laminate layers. A typical suitable knitted mesh material is knitted from two or more wire strands and forms a fairly open structure having, for example holes defined by the knitted wire strands of approximately lmm to 6mm in diameter. Each wire strand typically has a diameter of about 0. 2mm to 0. 5mm,

preferably about 0. 25mm. Suitable materials are widely available, for example from Knitmesh Ltd, Croydon, England.

A further preferred laminate layer of the material according to the invention comprises an aramid fibre (e. g. Kevlaflm) based sheet material. In a particularly preferred material, in order to save weight and/or cost, the material is made from a

cotton and Kevlar thread in a fine weave. Although Kevlar provides good resistance to cutting, in particular uses the cutting resistance may need to be improved. In this case, laterally and/or longitudinally extending pockets are woven into the material, so that the pockets form (when both lateral and longitudinal pockets are present) an intersecting grid of pockets. These pockets may then be threaded with a cut resistant wire rope or cable of metal or other suitably strong and flexible material, so that the wire follows a regular meandering path through the sheet of material. Preferably the wire is a single length of wire arranged to extend substantially throughout the pockets. Preferably, the spacing a spacing between adjacent pockets in the lateral or longitudinal direction is from about 25mm to about 150mm, preferably about 50mm to about 120mm. In a particularly preferred construction, the wire can take the form of multiple stranded wire rope of about 0. 5mm to 3mm diameter, preferably about 1. 5mm diameter in 7x7 strand formation.

Most preferably the wire rope is encased in a braided aramid fibre (e. g. Kevlar) tube to improve the resistance to cutting by side cutters and pliers.

In order to prepare a final laminate material according to the invention, it can be advantageous to bond the individual laminate layers together using a suitable bonding agent. This further increases the damage resistance of the laminate.

In the barrier materials according to the invention, the it is preferred that each of the above described layers is present. However, depending on the intended final use of the barrier material, and the strength and damage resistance which is required one or more of the layers may be omitted. Equally, more than one of the above described layers may be included where the required strength etc. is greater. Layers of other

materials which do not adversely affect the performance of the above layers may also be included if desired.

The laminate material according to the invention is very strong but relatively light.

The material is flexible and can be hung in the manner of a curtain or drape, allowing it to be drawn back from its position of use when not required.

In a particularly favourable arrangement, the laminate material may be incorporated into a curtain, roller shutter or blind construction. Preferably in this construction, the laminate material in the stored position of the shutter is mounted in roll form with the axis of the roll substantially vertical. The upper and lower edges of the laminate material are fitted with suitable engagement means or runners adapted to run in oppositely disposed tracks mounted, for example in the floor and ceiling of the opening which the shutter is intended to close. The runners may ideally be incorporated into a drive means such as a cable drive means with an electric motor by means of which the shutter may be moved into its closed and open (i. e. unrolled and rolled) positions. Locking means may be associated with the leading edge of the shutter so that, when in its closed position, the shutter may be opened only by authorised persons.

In one particular example of a security system including a shutter comprising the barrier material of the invention, the shutter, in conjunction with a second shutter or door defines a closed space. A control means provides that the shutter or the door respectively may only be opened when the other of the door and shutter is locked shut. In this way, access to a particular restricted area can be limited only to passage through the said closed space whereby at no time is the restricted area directly open to the exterior and, for example, identity checks can be made on persons seeking entry whilst in the closed space.

Claims

Claims 1. A barrier material suitable for limiting access to a designated area comprising at least one member selected from the group comprising: (i) at least one layer of a sheet material formed from an ultra high molecular weight polyethylene fibre ; and (ii) at least one layer of a sheet material formed from an aramid fibre.
2. A barrier material as claimed in claim 1 further comprising at least one layer of a knitted mesh material.
3. A barrier material as claimed in claim 1 or claim 2 comprising a laminate structure including at least one layer of a sheet material formed from an ultra high molecular weight polyethylene fibre and at least one layer of a sheet material formed from an aramid fibre.
4. A barrier material as claimed in claim 1,2 or 3 wherein the sheet material formed from an aramid fibre comprises cotton and aramid fibre thread.
5. A barrier material as claimed in claim 3 or 4 wherein the sheet material formed from and aramid fibre defined a plurality of intersecting pockets.
6. A barrier material as claimed in claim 5 further wherein the pockets are threaded with a cut resistant wire rope or cable following a meandering path through the sheet material.
7. A barrier material as claimed in claim 6 wherein a single wire rope or cable is arranged to extend substantially throughout the pockets.
8. A barrier material as claimed in claim 6 or 7 wherein the wire rope or cableis encased in a braided aramid fibre.

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9. A barrier material as claimed in any of claims 5 to 8 wherein the spacing between adjacent pockets is from about 25mm to about 150mm.
10. A barrier material as claimed in any preceding claim wherein respective layers of the material are bonded together.
11. A barrier material as claimed in any preceding claim comprising at least one layer of fire resistant or fire retardant material.
12. A barrier for controlling access to a designated area comprising a barrier material as claimed in any preceding claim.
13. A barrier as claimed in claim 12 in the form of a curtain, roller shutter or blind.
14. A barrier as claimed in claim 13 further comprising oppositely disposed tracks arranged on opposed sides of the curtain, roller shutter or blind and wherein the upper and lower edges of the curtain, roller shutter or blind are fitted with engagement means adapted to run in said tracks.
15. A barrier as claimed in claim 13 or 14 wherein the curtain, roller shutter or blind is moveable between extended and retracted conditions and in the retracted condition is arranged in the form of a roll with a substantially vertical axis.
16. A barrier as claimed in claim 15 further comprising drive means for movement of the barrier between the extended and retracted conditions.
17. An access control arrangement comprising a first curtain, roller shutter or blind as claimed in any of claims 13 to 16 in conjunction with a second curtain, roller shutter or blind or a door defining a closed space wherein the first curtain, roller shutter or blind or the second curtain, roller shutter or blind or a door may only be

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opened when the other of the second curtain, roller shutter or blind or a door or the first curtain, roller shutter or blind is locked shut.