WO2006092603A1

WO2006092603A1 - Treatment of long fibres in a high pressure gas stream

Info

Publication number: WO2006092603A1
Application number: PCT/GB2006/000747
Authority: WO
Inventors: Richard James Salisbury
Original assignee: University Of Wales, Bangor
Priority date: 2005-03-02
Filing date: 2006-03-02
Publication date: 2006-09-08

Abstract

A method of treating long fibres includes forming a sliver from resilient material fibres and feeding the sliver into a fast gas stream for treatment, e.g. application of fire retardant material or a dye.

Description

TREATMENT OF LONG FIBRES IN A HIGH PRESSURE GAS STREAM

This invention relates to a method of treating long fibres by feeding

them into a high pressure gas stream. The treatment may be the addition

of any suitable or desirable additive(s), blending with other materials,

drying, or changing the physical conformation of the fibres.

It has been known for many years that short fibres, as can be

derived from a wood material, can be coated with a resin material whilst

passing through a "blow line", of the type commonly used in apparatus

for forming medium density fibreboard (MDF), and can be transported

along the blow line at high speed by a stream of high pressure steam or

other suitable vapour or gas.

In the MDF process the short fibres are fed into the blow line

directly from the refiner in which they are produced. Long fibres cannot

be processed in this way for several reasons: because material containing

long fibres would block the valves used for feeding material into the

refiner, because the refining process would normally destroy long fibres,

and because any long fibres produced would rapidly block the entry to the

blow line.

The present invention is directed towards a method which

overcomes these problems and will allow fibres of any length which can

be processed by conventional textile machinery to be treated in a high

pressure gas stream in a similar manner as much shorter fibres. Thus and in accordance with the present invention, there is

provided a method for feeding relatively long fibres into a high pressure

gas stream for treatment comprising the steps of:

a) Selecting a suitable fibrous material;

b) Processing said material into fibres of a suitable length;

c) Forming said fibres into a suitable sliver form;

d) Feeding said sliver of material into a high pressure gas

stream by means of an apparatus keeps the gas flow

contained within the desired path;

e) Arranging for the turbulence in the gas stream where said

sliver is introduced to tear the sliver apart into individual

fibres or bundles of fibres and incorporate these into the flow

of gas; and

f) Treating said fibres, or bundles thereof, with a predetermined

material.

By feeding the sliver into a turbulent gas flow it is possible to

provide a system in which long fibres can be coated in a similar manner

as fibres which are used for the creation of MDF.

It has hitherto not been thought possible to coat or treat long fibres

of the type described above in this type of apparatus due to problems of

feeding long fibres into the blow line, and whilst blow line technology has

been used in the formation of MDF for many years, there has always been a technical prejudice against the use of this technology with longer length

fibres.

Any additive which is desired to be used to coat or treat the fibres

can be utilised as desired or as appropriate and therefore, for example

resins, dyes, fire retardant substances and fungicides could be used if it is

desirable to do so. In fact, any suitable additive material can be used so

long as it can be in a liquid form.

Preferably the material is of plant origin, for example bast fibres

from flax or hemp, seed fibres from cotton, leaf fibres from sisal. It is,

however, possible to use other material to form the fibres as desired or as

appropriate.

Preferably the length of the fibres utilised in the method of the

invention is in the range 20mm to 200mm, but any length that can be

processed by conventional textile machinery may be used.

The invention will now be described further, by way of example

only, and with reference to the single figure of the drawings which

shows, in block diagram form, the steps involved in one embodiment of

the method of the present invention.

The first step in the method shown is to select the material from

which the fibres are to be derived. As indicated in the introductory

paragraphs of the specification, the preferred materials for use would be

plant derived, for example flax or hemp but, of course, it will be

appreciated that any other suitable form of material from which fibres can be produced can be used as desired or as appropriate. For the purposes

of the present invention, the method will be described in relation to the

use of flax to produce the fibres.

The flax material is then processed into so-called "bast" fibres of

the required length. As mentioned previously, the preferred length of

fibre is in the range 20mm to 200mm and it is thought that the method of

the invention can work equally well at any point within this range. Well-

established technology is used to produce flax bast fibres of a suitable

length.

The separated flax bast fibres are then formed into a sliver. A

sliver is well known in the textile manufacturing field and consists of a

loose bundle of aligned fibres gathered from a carding machine.

Once the material has been formed into a sliver, it is transported into a

pressurised container where it can be fed into the fast gas stream where

it can be treated with any desired or suitable material. Thus, the fibres

can be treated by the introduction of a fire retardant material or,

alternatively, a dye could be introduced into the blow line in order to

colour the fibres if it is desired. Furthermore, it may be necessary to treat

the fibres with a resin material or a fungicide. The only restriction on the

material which can be used to treat the fibres is that it must be capable of

being in liquid form and must be able to withstand the conditions within

the blow line without degrading or otherwise adversely changing its

properties. The additives are applied to the fibres by injecting the desired

additive material in any suitable manner at any position in the pressurised

container or high pressure gas stream.

Once the steps of the invention have been carried out, it may be

desirable, although not essential, to pass the treated fibres into a drying

apparatus in order that any moisture can be eliminated from the fibres

prior to being collected. Once the fibres have been treated and are dry,

the fibres are collected and can be formed into any suitable product such

as, for example a filter, insulating material or composite.

The most important step in the method of the present invention,

and which allows the use of long fibres in such apparatus, is the method

by which the sliver of fibres is introduced into the high pressure gas

stream. Thus, the sliver is delivered to the high pressure gas stream

through a pressurised chamber and the turbulence is arranged to be of a

level such that the sliver is torn apart to a sufficient degree to prevent the

long fibres from clogging up the apparatus and to enable an even

distribution of additive at any level of addition.

It will of course to be understood that the invention is not intended

to be restricted to the details of the above embodiment which is

described by way of example only.

Claims

. A method for feeding relatively long fibres into a high pressure gas

stream for treatment comprising the steps of:

a) Selecting a suitable fibrous material;

b) Processing said material into fibres of a suitable length;

c) Forming said fibres into a suitable sliver form;

d) Feeding said sliver of material into a high pressure gas

stream by means of an apparatus keeps the gas flow

contained within the desired path;

e) Arranging for the turbulence in the gas stream where said

sliver is introduced to tear the sliver apart into individual

fibres or bundles of fibres and incorporate these into the flow

of gas; and

f) Treating said fibres, or bundles thereof, with a predetermined

material.

2. A method according to claim 1 wherein the additive used to coat

the fibre is a resin, dyes, fire retardant substances and/or a

fungicide.

3. A method according to claim 1 or claim 2 wherein the material is of

plant origin.

4. A method according to claim 3 wherein the length of fibres used in

the method is in the range 20mm to 200mm.