GB2078797A

GB2078797A - Continuous multifilament glass fibre roving is rendered coherent and catenary-free by passing it through an air treatment zone without positive overfeed

Info

Publication number: GB2078797A
Application number: GB8020414A
Authority: GB
Original assignee: TBA Industrial Products Ltd
Current assignee: TBA Industrial Products Ltd
Priority date: 1980-06-21
Filing date: 1980-06-21
Publication date: 1982-01-13
Also published as: NO812099L; FI69448C; NO152376B; EP0045560A1; AU7200281A; FI69448B; FI811908L; DE3167172D1; NO152376C; AU538483B2; EP0045560B1

Description

1

GB 2 078 797 A 1

SPECIFICATION

Improvements in and Relating to Glass Fibre Products

This invention relates to the processing of 5 continuous glass filaments and in particular it is concerned with the preparation of ravings from strands comprised of such filaments for conversion into fabrics by weaving and for use in the reinforcement of plastics, especially by the 10 pultrusion process.

A well-known problem in the preparation of such ravings is the phenomenon sometimes known as "catenary". This is the lateral separation of individual strands from an untwisted 15 roving made up of a bundle of such strands. It is caused by variations in tension present in the individual reel packages which are unwound and assembled side-by-side together to form the roving. "Catenary" gives rise to problems in 20 further processing and in the final conversion of the roving; various methods are known for minimising its effect. These methods include sizing treatments and twisting processes.

According to the present invention, a roving 25 comprising an untwisted bundle of continuous glass fibre filaments is passed through an air treatment zone without positive overfeed.

Air treatment zone in this context means a confined passageway into which air is introduced 30 under pressure. It has been found that relatively small air pressures and volume throughputs are highly effective to produce an essentially catenary-free strand, even with strand linear densities of from 3000 to 9000 tex and at strand 35 throughputs in the range 150—300

metres/minute. Air pressures of the order of 400 to 600 KN/metre2 and air volume throughputs of 0.5 to 1.5 cubic metres/minute are effective for present purposes; this is much less than would be 40 used in conventional air jet texturing processes; The present process has some similarity to the so-called co-mingling process, but the latter has hitherto been used for moderate texturing (bulking) of relatively fine manmade fibre yarns, 45 usually in conjunction with heating to "set" the bulk developed. A degree of positive overfeed is used to ensure that bulking is achieved.

By contrast, the present process when applied to a very much coarser glass fibre roving in the 50 complete absence of positive overfeed results in a roving which is essentially free from catenary. If the throughput is reduced towards 150 metres/minute, the product exhibits an apparent bulk. This bulk is only apparent, in the sense that 55 an applying moderate tension to the roving, it exhibits minimal or even zero extensibility,

coupled with practically no change in its catenary properties. This type of product has been found to be valuable for use as a plastics reinforcement, 60 particularly in pultrusion processes.

At roving throughputs of the order of 300 metres/minute the product is catenary-free and useful as a weaving grade roving.

A particularly advantageous aspect of the 65 invention lies in the fact that both of the two specific roving products just described can be made by incorporating the air treatment zone into the normal creelto-package winding operation, without introducing any separate extra processing 70 step. This is a particularly preferred embodiment of the invention; it comprises the steps of withdrawing individual continuous multifilament glass strands from each of a plurality of creel packages to form a single glass fibre roving, 75 passing said roving through an air treatment zone (as hereinbefore defined) without positive overfeed and thereafter winding the treated roving into a package.

A typical air treatment zone for present 80 purposes comprises a V-shaped trough with a hinged lid clampable in sealing relation thereto. A trough about 2.5 cm long and about 0.5 cm deep has been found satisfactory, the airflow being introduced halfway along the trough through an 85 aperture about 0.25 cm in diameter, in the bottom of the V. Obviously, the precise geometry of the air treatment zone may be varied and some experimentation may be necessary in order to arrive at the optimum conditions for a particular 90 roving and throughput.

Claims

1. A method of treating an untwisted multifilament roving of continuous glass filaments comprising passing said roving through an air

95 treatment zone without positive overfeed.

2. A method according to claim 1 wherein the roving is passed at a rate of from 150 to 300 metres a minute through an air treatment zone constituted by a confined passageway into which

100 air is introduced at 0.5 to 1.5 cubic metres/minute under a pressure of from 400 to 600 KN/metre2.

3. A method according to claim 1 or claim 2 wherein the roving linear density is from 300 to

105 9000 tex.

4. A method of producing an essentially catenary-free untwisted continuous multifilament glass fibre roving, the method comprising the steps of withdrawing individual continuous

110 multifilament glass fibre strands from each of a plurality of reel packages, assembling them side-by-side to form a single roving, passing said roving through an air treatment zone without positive overfeed, and thereafter winding the

115 treated roving into a package.

5. The method of claim 4 wherein the roving is passed at a rate of from 150 to 300 metres/minute through an air treatment zone constituted by a confined passageway into which

120 air is introduced at 0.5 to 1.5 cubic

GB 2 078 797 A 2

metres/minute under a pressure of from 400 to the roving has a linear density of from 300 to

600 KN/metre2. 5 9000 tex.

6. The method of claim 4 or claim 5 wherein

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.