GB2251253A

GB2251253A - Woven airbag

Info

Publication number: GB2251253A
Application number: GB9028170A
Authority: GB
Inventors: Jack Beedham
Original assignee: Airbags International Ltd
Current assignee: Airbags International Ltd
Priority date: 1990-12-28
Filing date: 1990-12-28
Publication date: 1992-07-01
Also published as: GB9028170D0

Abstract

An airbag woven on a loom and comprising at least an upper and lower fabric woven simultaneously is produced from yarns which have first boon treated with a permanent insoluble size. After weaving the fabric is heat treated whereby to set the size. Bags so produced have improved characteristics over bags not so treated. The size is preferably a polyether-type polyurethane or a high molecular weight polysiloxane or a combination of both. Other features of the airbag may be in accordance with WO 90/09295.

Description

AIRBAG This invention relates to an airbag and in particular relates to an inflatable airbag for the protection of vehicle occupants in the event of a collision.

Considerable interest is at present being shown in the wider application of airbag safety restraints for use in transportation. These are in general bags stored towards the front of the passenger compartment of the vehicle arranged to inflate rapidly in the event of a collision and thus restrain the occupant or occupants of the vehicle and prevent them being injured by being thrown against hard internal surfaces within the vehicle. Currently produce airbags, especially those for the drivers side, tend to be manufactured from a chlorobutadiene rubber coated polyamide fabric. Our PCT publication VTo/90/09295 discloses a method of manufacturing such an airbag where weaving on a loom in which upper and lower fabrics are formed simultaneously and combined at the edges to define the airbag shape.By controlling weave density, the permeability of the fabric can be selected to preclude the need for a coating.

In many weaving applications it is common to protect the yarn being woven by the application of a water soluble size to the yarn before weaving. After weaving, the size is removed from the woven fabric, for example by scouring.

The invention seeks to provide a method of producing airbags having improved properties.

According to the present invention there is provided a method of manufacturing an airbag by weaving on a loom which comprises forming at least an upper and lower fabric simultaneously and causing the two fabrics to be combined in selected areas of a desired shape whereby to define and enclose or substantially enclose space characterised in that yarns from which the fabrics are woven are first treated with a permanent insoluble size and that after weaving the fabric is heat treated whereby to set the size.

The use of a permanent size eliminates the need for scouring after weaving. Moreover, some or all of the following improved characteristics are obtained in accordance with the invention: 1. The yarn is made more hydrophobic and permeability of the finished airbag is less affected by changes in moisture content.

2. The burst strength of the fabric is increased which enables finer count yarns to be used further to reduce the bulkiness of the folded bag.

3. Reduced fibre to fibre friction produces less permeability at yarn cross-over points within the fabric after heat stabilisation.

4. The low friction characteristics of the finished bag produced by the size remaining in place results in faster deployment and less friction to the bag fabric during deployment.

5. The preferred size produces a lubricated and hence softer fabric resulting in less facial abrasion to the driver/passenger in deployment.

Preferred permanent sizes are chosen from polyether type polyurethanes or high molecular weight polysiloxanes or combinations of both. A particulary effective size is sold under the trade mark ELASTON D1024".

The size may be applied in the conventional manner for warp sizing. For example, unsized warp yarn is either passed through a bath containing "ELASTRON" or over lick rollers to apply the size evenly. The yarn is dried at 100-110 .

The increased weight due to size addition is in the region of 1%, after weaving the size is cured at 1500C for 3 minutes.

Other characteristics such as yarn count, weave pattern, type of loom, and loom setting may be set out in our above mentioned international publication number WO/90/09295.

The method of the invention allows bags of improved performance to be produced without increasing the weaving time or number of processing steps.

Claims

1. A method of manufacturing an airbag by weaving on a loom which comprises forming at least an upper and lower fabric simultaneously and causing the two fabrics to be combined in selected areas of a desired shape whereby to define and enclose or substantially enclose space, characterised in that the yarns from which the fabrics are woven are first treated with a permanent insoluble size and that after weaving the fabric is heat treated whereby to set the size.

2. A method as claimed in claim 1 in which the size is a permanent size.

3. A method as claimed in either of claims 1 or 2 in which the size is a polyether type polyurethane of a high molecular weight polysiloxane or a combination thereof.

4. A method as claimed in any of claims 1 to 3 in which the unsized warp yarn is passed through a bath containing the size.

5. A method as claimed in any of claims 1 to 3 in which the unsized warp yarn is passed over lick rollers to apply the size.

6. A method as claimed in either of claims 4 or 5 in which the yarn is dried at 100"C to Z1O"C.

7. A method of manufacturing an airbag substantially as hereinbefore described with reference to and as illustrated in the foregoing examples.