Dec at is Ing

8/3/2019 Dec at is Ing

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FABRIC AND GARMENT

FINISHING

ASSIGNMENT - I

ON

DECATISING

Submitted To:

Ms. T. Srivani

By:

Shreya Agarwal

Roll No. 24

DFT-IV

NATIONAL INSTITUTE OF FASHION TECHNOLOGY, HYDERABAD





Decatising

Decatising or decatizing, also known as crabbing, blowing, and decating, is the process of

making permanent a textile finish on a cloth, so that it does not shrink during garment

making.

Though used mainly for wool, the term is also applied to processes performed on fabrics of other fibers, such as cotton, linen or polyester . Crabbing and blowing are minor variations on

the general process for wool, which is to roll the cloth onto a roller and blow steam through

it.

Decatized wool fabric is interleaved with a cotton, polyester/cotton or polyester fabric and

rolled up onto a perforated decatizing drum under controlled tension. The fabric is steamed

for up to ten minutes and then cooled down by drawing ambient air through the fabric roll.

The piece is then reversed and steamed again in order to ensure that an even treatment is

achieved.

There are several quite different types of wool decatizing machines including batchdecatizing machines, continuous decatizing machines, wet decatising machines and dry

decatizing machines.

The aim of decatising is to stabilise the properties of the fabric developed in finishing.

Pressure Decatising

This is a batch process that provides conditions to achieve high levels of set. The principal

objectives of the process are to produce a permanent pressed finish with good handle, desired

lustre and dimensional stability for making up. The process involves winding the fabric onto

a large perforated cylinder/beam, interleaved with a wrapper fabric. Steaming is carried out in

a sealed chamber under pressure. Typical conditions are 1.0 Bar (120°C) but conditions varywith quality. Different steam flow directions are possible, e.g. in-out or visa versa and with

different steam pressures, cooling procedures and wrapper types. A range of finishes and

handle variations is therefore achievable.

Modern pressure decatising machines generally allow loading, unloading and processing

concurrently, giving high production. Cylinders are much larger than traditional machines,

allowing for increased loads, more uniform steaming and minimise end marking. This isimportant for reproducibility of finish. Absolute control of wrapper tension and axial

movement during winding (loading) reduces problems of wrapper collapse and bulky edgesto the batch.

Continuous high temperature and high pressure calendering/decatising/fixing method for

woollen fabric, wool mix, silk, cellulose, synthetic fabrics or non-fabrics, wherein the fabric

is subjected to steam treatment or treatment in super-heated water, the steam treatment or

treatment in super-heated water being performed by introducing the fabric inside a sealed

chamber , the sealed chamber being defined by at least four cylinders arranged in a foulard

configuration with adjustable pressure and by front sealing plates associated with the ends of



the cylinders , inside the sealed chamber at least one face of the fabric being in direct

contact with at least one of the cylinders.

"CONTINUOUS HIGH TEMPERATURE, HIGH PRESSURE CALENDERING/

DECATISING/FIXING METHOD FOR FABRICS AND RELATIVE DEVICE" * * * * *FIELD OF THE INVENTION This invention concerns a continuous high temperature, high

pressure calendering/decatising/fixing method for fabrics and the relative device as set forth

in the respective main claims.

The invention is applicable to the finishing cycles, after dying, of woollen fabrics, wool mix,

silk, cellulose or synthetic, non-fabric or similar, in order to permanently bestow on thecarded and combed fabrics the high characteristics of quality and the properties normally

required for a finished, ready-for-use fabric.

BACKGROUND OF THE INVENTION In the textile field the state of the art includesfinishing processes to which woollen fabric or similar is subjected to confer or fix particular

surface characteristics which enhance the quality or confer particular properties.

Among these finishing processes there is continuous calendering, which consists of makingthe fabric pass between two surfaces, generally metallic and pressing against each other, in

order to increase the compactness and shine of the fabric.

The two metallic surfaces are advantageously heated, normally by steam.

The calender normally consists of a hollow cylinder, which rotates on its axis, and a so-called

basin which is arc- shaped and also hollow so as to allow the heating steam to pass.

The basin presses against the cylinder, and the piece of cloth, which is drawn by the cylinder,flows over the

surface of an extremely smooth metallic sheet covering the basin.

The result of the calendering operation is a combination of two factors: the pressure of the

basin against the cylinder and the sliding friction of the fabric against the smooth surface of

the basin.

The first factor makes the fabric compact, the second makes it shiny.

Calendering has some undesirable consequences: the fabric may stretch due to the strong

drawing pressures, and it may be made too shiny, which is often unwanted.

The decatising treatment, which may be performed after or as an alternative to the

calendering process, substantially has the function of giving the fabric fullness of touch and

permanent stability.

If carried out in combination with calendering, decatising also serves to diminish any

excessive shininess of the fabric.



Decatising is based on the characteristic property of plasticisation of the wool fibre whenacted on by steam or water at high temperature.

Wool fibre, when acted on by steam, modifies its chemical/physical characteristics, and its

texture with respect to the surrounding fibres becomes permanent, particularly when thesubsequent cooling is done quickly.

There are many methods, in the state of the art, to carry out decatising.

A first, fundamental differentiation is between dry decatising, with steam, and wet decatising,with hot water.

A second differentiation is between continuous decatising and discontinuous decatising, that

is to say, with the piece of cloth staying stationary on the cylinder.

One dry decatising technique provides to wind the fabric

together with a sub-fabric on a holed cylinder from which a flow of water vapour emerges for

a determined period of time and at a determined pressure.

Dry decatising on the cylinder may be performed in the air, with the steam at a temperature of

98°C, or in an autoclave with the steam at a temperature which can reach 120-125°C.

Decatising in air with a temperature of 98°C is simple and economical, as a plant; however,

in functioning it causes disadvantages because of the considerable amount of steam requiredto replace what condenses and to heat the metallic parts.

Moreover, decatising with a semi-permanent effect is not always uniform, either in height or

in the various layers, and can cause a marbling effect, particularly in the inner layers.

Decatising in air, moreover, cannot easily be adapted in continuous decatising; machines

developed so far give regular processing but bland finishing effects.

Decatising in an autoclave provides to arrange the cylinder on which the fabric is wound in a

boiler or cistern which is under pressure and hermetically sealed; the steam is injected therein

at a temperature of 120. 125°C.

Using this method confers on the fabric a permanent feel and stability which cannot be

obtained with air decatising.

However, it is not possible to prevent discontinuity and irregularity in the processing;

moreover, the process requires a long time to carry out and high equipment costs.

Some improvements have been made in the process by working the fabric in an autoclave in a

damp state, with a humidity rate of between 20 and 80%, but even these improvements have

not been completely satisfactory.

Another evolution in the decatising process, as taught by



EP-A-293.028, has been the development of a decatising machine working continuously andunder pressure. Here, the fabric is accompanied like a"sandwich"between two pieces of felt

which wind continuously around portions of a cylinder, and is then subjected successively toa treatment with saturated, pressurised steam up to a temperature of 135°C and to a

subsequent step of cooling to stabilise the surface and the size.

Although this solution is conceptually valid, it has not had a real industrial success because of the technical problems inherent in the construction of the machine and the costs of the plant,

which are too high.

Furthermore, this embodiment has obvious irregularities in the processing which cause a

marbling effect and marking on the surface due to the presence of the two pieces of felt.

A further solution proposed to obtain an efficient decatising, combining the effects of high pressure, high temperature and mechanical pressure, is to combine the techniques of

calendering and decatising.

In practice, it has been suggested to wet the fabric before treating it, using pure water or

water to which chemical reducing compounds have been added, and then to transport it

sandwich-like between a heated cylinder, which carries out a steam treatment, and a belt or

other appropriate element which exerts thereon a defined surface pressure so as to obtain

steam at high temperature.

The rapid evaporation of the water with which the fabric is impregnated causes steam to

develop at a temperature of up to 135°C, which gives optimum conditions so that the

mechanical pressing performed by the pressing organs gives a very good fixing result.

There have been various proposals for techniques and the relative machines, more or less

sophisticated, for example

to accurately control the humidity content applied to the fabric as it enters the decatisingmachine so as to optimise the efficiency of the treatment.

By exploiting the principle of the combined effect of steam, temperature and pressure, a

plurality of constructors have proposed substantially similar machines, comprising a

cumbersome containing structure inside which there is housed a humidifier assembly,

followed by the pressing-steaming assembly followed in turn by a cooling assembly.

All the plants proposed and present on the market have not been used widely and

efficaciously due to their high cost, the large amount of space they occupy, their need for constant and costly maintenance.

Moreover, these plants have the problem that their productivity is very low.

Furthermore, the finishing effect is not always satisfactory and uniform for all types of fabric.

This is due to the fact that the stability effect of the fibres in a woollen fabric heated to a high

temperature using the humidity transformed into steam at high temperature is much less

accentuated than the effect obtained on a fabric steamed at high temperature with live steam.



Therefore, even the solutions described above do not obtain fully satisfactory results witheconomical and practical solutions.

The present applicant has tested and embodied this invention to overcome all these

shortcomings and to obtain further advantages.

SUMMARY OF THE INVENTION The invention is set forth and characterised in therespective main claims, while the dependent claims describe variants of the idea of the main

embodiment.

The purpose of the invention is to combine the teachings

of the state of the art to obtain a continuous calendering/ decatising/fixing treatment with high

temperature and high pressure steam wherein the fabric is subjected to a treatment with livesteam inside a sealed pressure chamber consisting of cylinders arranged peripherally in

contact and delimited at the front by sealing plates.

At the inlet and outlet of the sealed chamber, the fabric is subjected to a pressing action as it passes between the cylinders.

By using this procedure, the invention makes it possible to obtain, among other advantages, a

high level of compactness, a drapery finishing effect, a greater permanence of the fixing

effect on the fibres and a greater stability of size of the fabric.

The invention is embodied moreover as a very simple device, which requires limitedinvestment, is limited in size and requires very limited maintenance.

Moreover, the invention is extremely versatile and can be adapted to every type of fabric and

can obtain any type of result, inasmuch as it can be used to intervene easily and rapidly and

possibly to regulate an extremely high number of parameters so as to adapt to the needs of every occasion.

According to a variant, the fabric to be decatised is first dampened and then sent to a pressing

and steam treatment assembly where it is treated with live steam under pressure in a closed

chamber configured in the known form of a foulard.

In the case that the fabric should be dampened, there may also be included a suitable

humidifier assembly upstream of the sealed chamber, or the fabric may arrive at the devicealready dampened.

According to another variant, the fabric is introduced into the sealed chamber not dampened.

According to a further variant, the fabric is pre-heated before being sent into the sealed

chamber.

The foulard, for example but not exclusively in the form of four cylinders, defines a sealed,

pressurised chamber inside which the fabric is subjected to the action of the high pressure,

high temperature live steam.



According to the invention, the pressure of the live steam introduced inside the sealedchamber can reach maximum values of 4-6 atmospheres, while the temperature can reach up

to 140. 160°C.

At the inlet and outlet of the live steam treatment zone, the fabric is pressed between two pressing cylinders, with at least one possible accompanying element, such as a piece of felt or

similar, interposed.

In the sealed chamber, the fabric has one of its faces directly in contact with at least one of

the return and/or pressure cylinders.

At the outlet of the pressing and steam treatment assembly the fabric is then cooled in order to fix both the arrangement of the surface fibres and the size of the fabric.

This cooling treatment is achieved by subjecting the fabric to a current of cold air at a pre-

determined temperature.

According to a variant, the cooling treatment is achieved by using azote vapours.

According to a variant, the fabric emerging from the pressurised sealed chamber, before

being cooled is subjected to a steam treatment with steam at atmospheric pressure.

The pressurised sealed chamber wherein the live steam treatment is carried out is defined,

according to one embodiment of the invention, by a pressing cylinder at inlet, a pair of return

cylinders and by a pressing cylinder

at outlet.

According to a variant, the return cylinders also function as pressure cylinders.

The return cylinders, according to a variant, are driven and heated and have their surface

covered with steel, paper, ebonite, rubber, non-fabric fabric or similar material.

The pressure cylinders are also heated and, according to a variant, are covered with rubber.

According to a further variant, they are associated with means to regulate the pressure with

which they act on the fabric.

According to a variant, the return cylinders and/or the pressure cylinders are associated with

means to regulate the temperature.

According to another variant, the pressure cylinders and the return cylinders have lining ringsmade of hard rubber at their ends; these cooperate by friction with lateral sealing plates

associated with thrust means.

The rings of hard rubber, according to a further variant, may be associated with lubricationmeans, for example with a mixture of air and water or with air mixed with oiling and/or

lubricating products.



According to another embodiment of the invention, inside the sealed chamber the fabric issubjected to a treatment with super-heated water at a maximum temperature of around 140°C

and a maximum pressure of around 4 bar.

This embodiment is preferentially used on 100% woollen products or wool mix, either raw or dyed, to ensure a permanent fixing.

The device adopted for this embodiment is substantially the same as the one which achieves

the steam treatment, with the exclusion of the dampening process before the fabric enters the

sealed chamber and the steam treatment at the

outlet thereof.

The circuit to feed the steam, or the super-heated water, inside the sealed chamber comprisesvalve means to regulate the pressure, advantageously located both at the inlet and the outlet

of the chamber, by means of which it is possible to regulate the pressure of the steam or water introduced.

According to another variant, when steam treatment is used, the sealed chamber has breather

means to discharge any possible condensation which might have accumulated during the processing.

The procedure according to the invention, according to the type of fabric to be treated and/or the type of result to be obtained, provides to intervene on one and/or another of the following

parameters: -pressure and/or temperature of the steam or water; -tension of the accompanyingelement, if any, interposed between the fabric and the pressing cylinders; -pressure of the

inlet and/or outlet pressing cylinder and/or of the return cylinders; -temperature of the pressing cylinders and/or the return cylinders ; -speed of feed of the fabric; -intensity of the

cooling treatment and/or the steam/ cooling; -dampening of the fabric upstream of the steam

treatment; -type of lining used for the cylinders.

BRIEF DESCRIPTION OF THE DRAWINGS The attached Figures are given as a non-

restrictive example and show some preferential embodiments of the invention as follows: Fig.

1 shows a first embodiment of the calendering/decatising/fixing device according to the

invention;

Fig. 2 shows a first variant of Fig. 1; Fig. 3 shows a second variant of Fig. 1; Fig. 4 shows a

third variant of Fig. 1; Fig. 5 shows a fourth variant of Fig. 1; Fig. 6 is a diagram of the

sealing system and the system to feed steam inside the sealed chamber according to the

invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The attached Figures1-5 show possible embodiments of the calendering/decatising/fixing device 10 for fabrics 11

according to the invention, in diagram form.

In the embodiments shown, the fabric 11 is first dampened by being passed through a

humidifier device 12 until it reaches a desired rate of humidity; then it is pre-heated and sent

inside a sealed chamber 13 inside which a pressurised environment is created by means of

introducing high pressure, high temperature live steam.



The humidifier device 12 can be omitted, in which case the fabric 11 can arrive alreadydampened by an appropriate assembly upstream, or it may not be dampened.

The pressures which may be reached inside the sealed chamber 13 may have values of up to

4-6 atmospheres, while the temperatures attainable may be as much as 140-160°C.

According to a variant which is not shown here, the fabric 11 is subjected inside the sealedchamber 13 to treatment with water super-heated to a maximum temperature of 140°C, there

not being included, in this case, any humidifier device 12.

In this case, the sealed chamber 13 is defined by four cooperating cylinders, respectively two

counter-opposed pressure cylinders 14a and 14b, and two counter-opposed return cylinders15a and 15b.

According to variants which are not shown here, the device

10 comprises six or more cylinders arranged so as to constitute several sealed chambers 13

through which the fabric 11 is made to pass in succession.

Each of the return cylinders 15a and 15b, which may also have a pressure function, has its

respective surface tangent to the surface of both the pressure cylinders 14a and 14b so that the

four respective lines of tangency 16a, 16b, 16c and 16d define the limits of the sealed

chamber 13.

The inlet return cylinder 15a also has the function of pre-heating the fabric 11 before it entersthe sealed chamber 13.

Before entering the sealed chamber 13, the fabric 11 is made to pass on an inlet return

cylinder 21 which causes it to wind onto a defined arc of the heated return cylinder 15a.

At the front, the sealed chamber 13 is defined by sealing plates 17 cooperating with the ends

of the cylinders 14a, 14b and 15a, 15b.

The plates 17 cooperate by friction, in this case, with rings 18 made of hard rubber and

applied to the ends of the cylinders 14a, 14b, 15a, 15b. The plates 17 are associated with

compression means 19 which ensure that the sealed chamber 13 is maintained sealed with

respect to the outer environment.

The rings 18 of hard rubber may cooperate with a lubrication system, which is not shown

here, which acts, for example intermittently, delivering a lubrifying flow based on a mixtureof air and water or air to which oiling products or lubricants of another type have been added.

The fabric 11 is introduced inside the sealed chamber 13 through an inlet pressure zone,

defined by the line of tangency 16a between the pressure cylinder 14a and the return cylinder

15a.

In this case, the fabric 11 is pressed along the line of tangency 16a with an accompanying

element interposed; the said element consists of a piece of felt 20 which, in Fig.



1, winds around the arc of the return cylinder 15a inside the sealed chamber 13, the pressurecylinder 14b and the return cylinders 21.

The surface of the fabric 11 subjected to treatment is in direct contact with the relative return

cylinder 15a so that pressure is exerted in a regular and uniform manner without marbling or marking the surface.

The accompanying element interposed between the cylinders and the fabric 11 may consist,

apart from a piece of felt, of a strip made of polyester, polyester-wool, wool, cotton or of

another suitable material, even synthetic.

The material which constitutes the accompanying element 20 will vary according to whether the treatment is achieved with live steam or in super-heated water.

The return cylinders 21 may have an adjustable position so as to vary the tension imparted to

the fabric 11 compressed by the pressure cylinders 14a and 14b.

The pressure cylinders 14a and 14b, in this case, are covered by a layer of rubber 22 and can be regulated radially in the direction of the arrows 23 to regulate the intensity of the pressure

on the fabric 11.

By regulating the pressure acting on the fabric 11, on the one hand it is possible to guarantee

that the sealed chamber 13 remains sealed, and on the other hand to regulate the level of pressure on the fabric 11 entering the sealed chamber 13 or emerging therefrom.

The return cylinders 15a and 15b are driven and are covered by a lining made of rubber,

ebonite, steel, paper, non-fabric fabric or similar material. The pressure cylinders 14a and 14band the return cylinders 15a and 15b

are also associated with heating means which include the possibility of regulating their temperature according to the type of fabric 11 and the result of the treatment to be obtained.

The material which lines the return cylinders 15a and 15b and the pressure cylinders 14a, 14b

will also vary according to the type of treatment performed inside the sealed chamber 13.

The fabric 11 emerging from the sealed chamber 13 and the treatment with steam or super-

heated water is sent to a cooling system 24.

In the case shown in Fig. 1, the cooling system comprises a plane of feed with a conveyor

belt 25 over which the fabric 11 passes; a ventilation system acting from above cooperatestherewith.

The cooling flow can consist of air or mixtures of steam- air or other cooling fluids, such as

for example azote vapours.

The cooling flow can also be sent from below through holes included on the plane of feed-

conveyor belt 25.

In the variant shown in Fig. 2, the cooling system 24 comprises a holed cylinder 26

cooperating along one of its arcs with a compression system consisting of a piece of felt 120



which acts as an accompanying and pressure element and is guided by return cylinders 121against the fabric 11.

In the variant shown in Fig. 3, the fabric 11 emerging from the steam treatment zone inside

the sealed chamber 13 is made to cooperate with a steaming assembly 27 while it is windingaround the cooling cylinder 26 and is pressed against the cylinder 26 by the piece of felt 120.

Following the steaming treatment, the fabric 11 is subjected to cooling by delivering a

cooling fluid from the cylinder 26.

In the variant shown in Fig. 4, the fabric 11 is introduced into the sealed chamber 13 without

being accompanied by the piece of felt.

In the further variant shown in Fig. 5, in order to ensure a prolonged action of compressionafter the steam treatment, the fabric 11, together with the piece of felt 20, follows a winding

path around the pressure cylinder 14a inside the sealed chamber 13, and then winds for thewhole arc of the return cylinder 15b outside the sealed chamber 13.

Then, it re-enters inside the sealed chamber 13, winding around the arc of the pressure

cylinder 14b, and is then sent to the cooling system 24, where it winds around the coolingcylinder 26 in cooperation with the piece of felt 120.

Fig. 6 shows a diagram of a system to introduce the steam inside the sealed chamber 13,defined by the cylinders 14a, 14b, 15a and 15b, wherein there is a conduit 28 associated with

an inlet valve 29a and with an outlet valve 29b and with a condensation separator 30 placedat the inlet.

The valves 29a and 29b make it possible to regulate the pressure and quantity of the steam

introduced inside the sealed chamber 13 so as to obtain the desired treatment of the fabric 11.

There are also valves which are not shown here to discharge any possible condensation before the steam is introduced inside the sealed chamber 13.

What is decatising?

Decatizing (or decatising) mainly imparts dimensional stability to the textile fabrics.

Also creases are removed and the fabric is smoothened. Here the principle involved

is controlled relaxation of strains stored in a fabric. Fabric along with a felt are rolled

in open width onto a perforated cylinder and subjected to super heated steam. Here

it is important that the wool felt used should not be so hard that the silk fabric is not

pressed flat.Use: Wool and wool blends as well as synthetic fibres, e.g. in the automotive field,

especially also for blends with viscose and cotton.

This is a continuous decatizer working with the evaporation system. Important is the

defined and adjustable moisture application at machine entry. By the action of

temperature and pressure the moisture applied is converted into steam, an

impermeable pressure belt prevents escaping of the steam. Fabric run throughout

the machine is absolutely at minimum of tension. By heating pressure belt and effect



cylinder and through the surface pressure produced by the tensioning roller, HT

conditions are achieved. The higher the pressure, the higher the fabric temperature ±

up to 140°C.

Conventional continuous decatizers work with the suction principle by which

temperatures of only up to 105°C can be achieved. Touch, lustre, volume, degree of

fixation and elasticity can be influenced within wide bounds through humidity,temperature and pressure whereby the height of temperature is a decisive factor.

Abstract

A method and apparatus for continuously pressure decatising a fabric include a rotatable drum (12) around which an endless

belt (15) is arranged to travel for conveying a fabric (19) (and optionally a moisture laden textile (20)) between the facing

surfaces of the belt (15) and the drum (12). The drum (12) is heated and fabric (19) is pressed between the belt and the drum

as it is conveyed through the apparatus. The fabric (19) is subjected to pressurized saturated steam, which may be generated

by evaporation of the moisture in textile (20) when it contacts the heated drum, as it is pressed. Various options other than use

of a moisture laden textile (20) for supplying the steam are disclosed. The invention involves enclosing the drum in a pressure

vessel (14) within which a compressed air atmosphere at ambient temperature is maintained. The surrounding compressed air atmosphere can be used to control the steam temperature, that is, the saturated steam temperature can be changed by

changing the pressure of the surrounding compressed air. The surrounding compressed air atmosphere also reduces the

sealing requirements for the steam treatment and belt wear. The method and apparatus are also applicable for setting staple

fibers.

What is claimed is:

1. A method for continuously pressure decatising a fabric including the steps of

(i) establishing a region of compressed gas having a predetermined pressure,

(ii) continually conveying a fabric through the region of compressed gas by and between two conveying members,

(iii) applying saturated or superheated steam at a high t emperature to the fabric within the region of compressed gas and

simultaneously pressing the fabric between the two conveying members,

wherein the high temperature of the saturated or superheated steam is determined substantially by the predetermined pressure

of the region of compressed gas.

2. A method as claimed in claim 1 including heating one of said two members such that moisture contained in or on the fabric is

evaporated to thereby provide the saturated or superheated steam.

3. A method as claimed in claim 1 including continuously conveying a moisture laden textile material through the region of



compressed gas by and between said two conveying members such that the moisture laden textile material is in facing contact

with the fabric, and heating the one of said two conveying members that is adjacent the moisture laden textile material such

that the moisture contained in or on that textile material is evaporated to thereby provide the saturated or superheated steam.

4. A method as claimed in claim 1 wherein the two conveying members are permeable and the saturated or superheated steam

is passed through the two conveying members for application to the fabric from a pressurized supply of the steam.

5. A method as claimed in claim 1 including an additional step of passing gas through the fabric to cool the fabric and reduce its

regain while the fabric is pressed between the two conveying members for stabilising the fabric.

6. A method as claimed in claim 5 wherein the additional step is conducted within the region of compressed gas.

7. A method as claimed in any one of claims 1 to 6 wherein the predetermined pressure of the region of compressed gas is

varied to thereby vary the high temperature of the saturated or superheated steam.

8. A method as claimed in any one of claims 1 to 6 wherein the compressed gas is air at ambient temperature.

9. A method for setting staple fibers wherein the fibers are contained in an assembly of fibers comprising a sliver, roving,

strand, or yarn, the method including the steps of


(ii) continually conveying the assembly of fibers through the region of compressed gas,

(iii) applying saturated or superheated steam at a high temperature to the assembly of fibers within the region of compressed

gas and simultaneously constraining the fibers in the assembly of fibers.

10. Apparatus for continuously pressure decatising a fabric including first and second conveying members for continuously

transporting a fabric along a predetermined path, wherein each conveying member includes a facing surface and the fabric is

pressed between the facing surfaces as it is transported by the first and second conveying members along the predetermined

path, wherein a treatment zone for the fabric is substitutively defined by the facing surfaces of the first and second conveying

members and a portion of the length of the predetermined path; drive means associated with the first or the second conveying

member for moving said first or second conveying member for transporting the fabric; means for providing a saturated or

superheated steam atmosphere within the treatment zone; and a pressure vessel for containing a compressed gas; wherein the

treatment zone is contained within the pressure vessel and wherein the pressure of the compressed gas is controllable to

thereby controllably establish a high temperature for the saturated or superheated steam atmosphere within the treatment

zone.

11. Apparatus as claimed in claim 10 wherein the means for providing a saturated or superheated steam atmosphere within the

treatment zone includes a heating arrangement associated with the first or the second conveying member, wherein the heating

arrangement heats its associated first or second conveying member for evaporating moisture contained in or on the fabric when

the fabric contacts said heated conveying member.

12. Apparatus as claimed in claim 11 wherein the first and second conveying members are impermeable.

13. Apparatus as claimed in claim 10 wherein the means for providing a saturated or superheated steam atmosphere within the

treatment zone includes a heating arrangement associated with the first or the second conveying member and a moisture laden

textile material, wherein the moisture laden textile material is arranged to be transported through the treatment zone together

with the fabric to be decatised between the facing surfaces of the first and second conveying members with the moisture laden

textile material lying adjacent the facing surface of the conveying member with which the heating arrangement is associated,

wherein the heating arrangement heats its associated first or second conveying member for evaporating moisture contained in

or on the moisture laden textile material when that material contacts said heated conveying member.

14. Apparatus as claimed in claim 13 wherein said first or second conveying member which is not associated with the heating

arrangement is permeable.

15. Apparatus as claimed in claim 10 including a heating arrangement associated with the first or the second conveying

member, wherein the first and the second conveying members are permeable and wherein the means for providing a saturated

or superheated steam atmosphere within the treatment zone includes a chamber for providing a pressurized supply of steam,

wherein the chamber is arranged for steam to pass therefrom through the first and the second conveying members and thus

through a fabric therebetween.

16. Apparatus as claimed in claim 10 wherein the first conveying member is a drum which is mounted for rotation within the

pressure vessel, and wherein the second conveying member is an endless belt which enters the pressure vessel at an entry

aperture, travels around the drum and then exits the pressure vessel at an exit aperture adjacent its entry aperture, wherein

seals are provided at the entry and exit apertures in the pressure vessel for maintaining the pressure of a compressed gas



therein, wherein a fabric is continuously transportable through the pressure vessel when sandwiched between the endless belt

and surface of the drum, wherein the means for providing a saturated or superheated steam atmosphere within the treatment

zone includes a heating arrangement associated with the drum for heating its facing surface.

17. Apparatus as claimed in claim 16 wherein the drum and the endless belt are impermeable, and wherein the heating

arrangement associated with the drum for heating its facing surface is for evaporating moisture contained in or on the fabric

when the fabric contacts said healed drum surface.

18. Apparatus as claimed in claim 16 wherein the drum is impermeable and the endless belt is permeable, wherein the meansfor providing a saturated or superheated steam atmosphere additionally includes a moisture laden textile material which is

transportable through the treatment zone, together with the fabric to be decatised, between the facing surfaces of the drum and

the fabric, wherein the heating arrangement heats the facing surface of the drum for evaporating the moisture contained in or

on the moisture laden textile material when that material contacts said heated facing surface.

19. Apparatus as claimed in claim 16 wherein the drum and the endless belt are permeable and the means for providing a

saturated or superheated steam atmosphere within the treatment zone includes a chamber for providing a pressurized supply

of steam, wherein the chamber is arranged for steam to pass therefrom through both the drum and the endless belt with the

fabric therebetween.

20. Apparatus as claimed in claim 19 wherein the chamber is located inside the drum such that the pressurized steam enters

the treatment zone through the drum.

21. Apparatus as claimed in claim 19 wherein the chamber is located over the endless belt such that the pressurized steam

enters the treatment zone through the endless belt.

22. Apparatus as claimed in claim 20 wherein a further chamber is located inside the drum for passing pressurized gas at

ambient temperature through the fabric after it passes the first defined (steam) chamber for cooling and drying the fabric within

the pressure vessel.

23. Apparatus as claimed in claim 21 wherein the chamber extends around a portion of the circumferential surface of the drum

such that a further portion thereof is available for gas from the pressure vessel to pass through the fabric for cooling and drying

the fabric within the pressure vessel.

24. Apparatus for setting staple fibers wherein the fibers are contained in an assembly of fibers comprising a sliver, roving,

strand, or yam, the apparatus including means for conveying the assembly of fibers through a t reatment zone, means for

constraining the fibers as they pass through the treatment zone, means for providing a saturated or superheated steam

atmosphere at a high temperature within the treatment zone, and a pressure vessel for containing a pressurized gas, wherein

the treatment zone is contained within the pressure vessel and wherein the pressure of the compressed gas is controllable to

thereby controllably establish ;a high temperature for the saturated or superheated steam atmosphere within the treatment

zone.

Description:

This invention relates to a method, and apparatus for performing the method, for the continuous pressure decatising of fabrics.

The invention also extends to a method and apparatus for continuously setting staple fibers, wherein the staple fibers are

contained in an assembly of fibers such as a sliver, roving, strand, yarn or the like. The invention is particularly suitable for

setting wool fibre assemblies and decatising woollen and wool containing fabrics (hereinafter the term wool fabric or the like is

to be understood as encompassing fabrics containing a mixture of wool and another or other fibers) and will be described

hereinafter with reference to such fibers and fabrics, but it is to be understood that the invention is applicable to other staple

fibers, and to other fabrics such as, for example, cottons and rayons which are generally decatised to set the material, enhance

lustre or impart some dimensional stability.

Pressure decatising is a finishing treatment whereby a wool fabric's physical and dimensional form is enhanced and then

stabilised by the use of heat, moisture, pressure and time. Generally, a pressure decatising method produces a permanent

change in fabric properties by the action of heat and pressurised steam at greater than 100 kPa (1 atm) pressure on amechanically constrained fabric, and is usually performed during the final stages of fabric production for several reasons:

(a) to develop desirable aesthetic qualities in the fabric such as handle, lustre and smoothness,

(b) to improve the dimensional stability of the fabric particularly for purposes of garment assembly, and

(c) to permanently set or preserve these qualities during fabric use. A continuous pressure decatising method imparts a

permanent finish to a fabric in two distinct operations, fabric relaxation/setting followed by fabric stabilisation, For fabric

relaxation/setting, the fabric is for example subjected to mechanical compression in an ambient of steam at high pressure and

temperature, which allows the fibers to relax and adopt a new conformation. For fabric stabilisation, the fabric undergoes

cooling and drying processes which set the fabric in its new conformation and also bring it back to room ambient. Similarly,



individual fibers in an assembly of staple fibers can be treated by heat and pressurised steam whilst mechanically constrained,

and then be cooled and dried to set them.

One known type of continuous decatising apparatus comprises a perforated heated drum having an endless belt held in tension

and wrapped around most of the circumference of the drum. The fabric, which it conveyed between the surface of the drum and

the belt as the drum rotates, is thus pressed between the drum and the belt surface. Besides being heated by the drum, the

fabric is also subjected to steam which is introduced through the drum perforations. Alternatively a laminar-shaped enclosure

may be formed between an impermeable pressure belt and an unperforated drum. Pressurised steam is generated in this

enclosure by vaporisation of moisture carried in by the belt-fabric sandwich. The "Super finish-GFP" machine made byMenschner (now MTECH) provides an example of this latter apparatus.

The pressure belt in this known type of apparatus simultaneously compresses and seals the fabric against the rotating drum.

However the level of permanent set that can be imparted to the fabric is limited by the tensile strength of the pressure belt

because it is the tension in this belt that provides the seal to maintain a saturated atmosphere within the fabric to set the fibers.

Furthermore, the belts in this apparatus wear quickly and require frequent periodic and thus costly maintenance because of

their continuously high tensile stress and high temperature working conditions. A further problem with this apparatus arises

from the dual role of the pressure belt, that is, it must simultaneously form a high pressure seal with the drum and also apply

mechanical pressure to the fabric. To make a leak-tight seal with the drum, the sealing pressure exerted by the belt must

exceed the pressure of the enclosed steam, but the mechanical pressure actually applied to the fabric will be reduced by the

"cushioning" effect of this steam. Consequently it is difficult to control the fabric compression as it will depend on the steam

pressure within the enclosure.

Another known type of continuous pressure decatising apparatus, of which the "Ekofast" machine developed by WIRA (Wool

Industries Research Association) and Mather & Platt provides an example, involves transporting the fabric between two endless belt conveyors through an autoclave containing saturated steam. At least one of the conveyors is permeable and the fabric

is subjected to impulsive compression by nip rollers. The belt conveyors in this apparatus are tensioned to maintain a desirable

fabric finish. Although this tensioning is not as high as in the first described known apparatus, the belts have to be permeable

and belt wear is still a problem. This apparatus can impart a reasonable permanent finish to wool fabric, however the required

treatment time is much longer than that in the first described known apparatus.

Generally, known continuous pressure decatising apparatus require complex sealing arrangements due to the need to seal an

enclosure of saturated steam at high pressure and yet allow a fabric to enter the enclosure, flat set and emerge from the

apparatus in a continuous fashion. Example disclosures which deal With this sealing problem for continuous decasting

apparatus are provided by European Patent 0533295 and International Application No. PCT/IT92/00114 (WO94/10367). A

further problem is the need to ensure adequate insulation of the enclosures of saturated steam.

In summary, known continuous pressure decatising methods and apparatus involve problems with belt wear, the sealing of

enclosures for saturated steam and insulating those enclosures. The solutions to these problems offered to date tend to be

complex and thus costly. Furthermore, it has been difficult to date to closely control and readily adjust the steaming conditions,

namely the temperature of the saturated or superheated steam to which a fabric is subjected during a continuous decatising

method.

The present invention is based on the realisation that the steaming conditions in a continuous pressure decatising method may

be controlled using a surrounding pressurised atmosphere, preferably of air and preferably at ambient temperature, and

controlling the pressure of that atmosphere, and that such a surrounding atmosphere could also reduce the belt wear, sealing

and insulation problems of the prior art. It wag also realised that this principle of using an enclosing compressed gas for

controlling steaming conditions could be applied more generally for the setting of staple textile fibers as such.

Accordingly, in a first aspect of the present invention, there is provided a method for continuously pressure decatising a fabric

including the steps of

(i) establishing a region of compressed gas having a pre-determined pressure,

(ii) continually conveying a fabric through the region of compressed gas by and between two conveying members,

(iii) applying saturated or Superheated steam at a high temperature to the fabric within the region of compressed gas and

simultaneously pressing the fabric between the two conveying members,

wherein the high temperature of the saturated or superheated steam is determined substantially by the predetermined pressure

of the region of compressed gas.

In a second aspect, the invention provides a method for setting staple fibers wherein the fibers are contained in an assembly of

fibers such as a sliver, roving, strand, yarn or the like, the method including the steps of




(ii) continually conveying the assembly of fibers through the region of compressed gas,

(iii) applying saturated or superheated steam at a high temperature to the assembly of fibers within the region of compressed

gas and simultaneously constraining the fibers in the assembly of fibers,

wherein the high temperature of the saturated or superheated steam is determined substantially by the Predetermined pressure

of the region of compressed gag

The method of the first and second aspects of the invention may additionally include a step of passing cool gas through thefabric, or the assembly of fibers, to cool it and reduce its regain whilst the fabric is pressed between the two conveying

members, or whilst the assembly of fibers is constrained, for stabilising the fabric or the fibers. This additional step is preferably

also conducted within the region of compressed gas.

According to a third aspect of the invention, there is provided apparatus for continuously pressure decatising a fabric including

first and second conveying members for continuously transporting a fabric along a predetermined path, wherein each

conveying member includes a facing surface and the fabric is pressed between the facing surfaces as it is transported by the

first and second members along the predetermined path, wherein a treatment zone for the fabric is substantively defined by the

facing surfaces of the first and second members and a portion of the length of the predetermined path; drive means associated

with the first or the second member for moving said first or second member for transporting the fabric; means for providing a

saturated or superheated steam atmosphere within the treatment zone; and a pressure vessel for containing a compressed

gas; wherein the treatment zone is contained within the pressure vessel and wherein the pressure of the compressed gas is

controllable to thereby controllably establish a high temperature for the saturated or superheated steam atmosphere within the

treatment zone.

According to a fourth aspect of the invention, there in provided apparatus for setting staple fibers Wherein the fibers are

contained in an assembly of fibers such as a sliver, roving, strand, yarn or the like, the apparatus including means for

conveying the assembly of fibers through a treatment zone, means for constraining the fibers as they pass through the

treatment zone, means for providing a saturated or superheated steam atmosphere at a high temperature within the treatment

zone, and a pressure vessel for containing a pressurized gas, wherein the treatment zone is contained within the pressure

vessel and wherein the pressure of the compressed gas is controllable to thereby controllably establish a high temperature for

the saturated or superheated steam atmosphere within the treatment zone.

Preferably the compressed gas is air at ambient temperature. Thus, according to the invention, it is possible to change the

saturated steam temperature by adjusting the pressure of the surrounding compressed air. The temperature of saturated steam

at a given pressure is obtainable from Steam Tables at the equivalent vapour pressure. Also, with such a pressurised

atmosphere, the sealing of the treatment zone is not critical because of the surrounding high air pressure. That is, because of

the surrounding high air pressure, localized saturated (or superheated) steam is effectively maintained in the treatment zone

(the degree of leakage of steam that may occur from the treatment zone is insignificant to the functioning of the decatising

process). Thus the first and second conveying members may be permeable or impermeable.

The treatment zone for the fabric is generally the space between the facing surfaces of the two (or the first and second)

conveying members over a length of the path of the fabric through the apparatus and there are various options available for

providing a saturated or superheated steam atmosphere within this zone. At least one of the conveying members should be

heated for the decatising (and thus it will have a heating arrangement associated with it) and this heating may be employed for

generating the steam.

Thus a saturated or superheated steam atmosphere can be established within the treatment zone, simultaneously with the

pressing and conveying of a fabric therethrough, by appropriately heating one of the conveying members such that moisture on

or in the fabric is rapidly evaporated. Preferably moisture is applied to the fabric prior to its passage through the treatment zone.

This can be done by spraying a surface of the fabric with moisture, which surface should be the one that faces the facing

surface of the heated conveying member. Alternatively, a moisture laden textile material can be arranged to travel through the

treatment zone sandwiched between the fabric being treated and the facing surface of one of the conveying members, which

facing surface is suitably heated so as to rapidly evaporate the moisture that is conveyed into the treatment zone by the textile

material. In this situation a permeable belt conveying member may be used in order to release excess moisture from the fabric

during treatment.

In an alternative aspect, a process and apparatus according to the invention includes introducing steam into the treatment zone

through the first conveying member or the second conveying member, or both, which will require that the conveying member(s)

concerned be permeable. For example, one of the conveying members may be a rotatable drum and steam may be introduced

into the treatment zone from inside the drum via suitable perforations through its surface. In another example, wherein the first

and second conveying members comprise a permeable belt travelling over a drum, a steam chamber or the like may be

provided over a portion of the belt over the drum (effectively the belt/drum interface provides a wall for the chamber). Thus in

this example, pressurized steam is introduced into the treatment zone through the belt. The enclosure of such a steam

chamber in a pressurized atmosphere such as compressed air, according to the invention, helps maintain the saturated steam

at a temperature corresponding to this pressure and alleviates the sealing requirements for the chamber relative to the belt,

thus reducing a problem which exists with prior art arrangements that employ similar steam chambers.



The first and second conveying members could be constituted by endless belt conveyors. Preferably, however, the first

conveying member is a heated cylindrical drum, the outer surface of which provides one of said facing surfaces, and the

second conveying member is an endless belt that travels around the drum whereby fabric, which is sandwiched between the

drum and the belt, can be continuously conveyed through the apparatus via rotation of the drum. Thus, the drive means

associated with the first or second member may be a driving arrangement for rotating the drum.

In this preferred drum and belt arrangement for the apparatus of the invention, the facing surface of the belt is not required to

establish a seal with the facing surface of the drum along the longitudinal edges of a fabric. All that is required of the belt is thatit be tensionable to exert sufficient lateral pressure to maintain a desired finish on the fabric.

In the above described preferred form of apparatus for the invention, the drum may be mounted for rotation within a pressure

chamber with the belt arranged to enter and exit the chamber through suitable sealing arrangements. Compressed air at room

temperature can be supplied to the chamber to maintain a suitable pressure therein while the fabric travels through. This

arrangement allows for ready variation of the pressure within the chamber.

Embodiments of the invention will now be described, by way of non limiting example only, with reference to the accompanying

drawings.

FIG. 1 shows a simplified diagrammatic illustration of an apparatus for the continuous decatising of a fabric according to the

invention.

FIG. 2 is a diagrammatic illustration for explaining the operation of the invention according to a first embodiment thereof.

FIG. 3 is a similar illustration to FIG. 2 relating to a second embodiment of the invention.

FIG. 4 is also a similar illustration to FIG. 2 relating to ;a third embodiment of the invention.

FIG. 5 shows a further embodiment of apparatus according to the invention, and

FIG. 6 shows a modified form of the FIG. 5 apparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

The apparatus 10 shown in the FIG. 1 illustration includes a steel drum 12 which is mounted for rotation, about a shaft 13,

within a pressure vessel 14. Preferably pressure vessel 14 is cylindrical (as illustrated), although it may be any other suitable

shape. An endless belt 15 is arranged around a series of eight rollers 16 such that it travels into vessel 14 through an entry

aperture 17, around about 80% of the circumferential surface of drum 12 and then out an exit aperture 18. One of the rollers 16

is adjustable in a known way for adjusting the tension in belt 15, also shaft 13 or one of the rollers 16 is driven. A fabric 19 is

fed to the apparatus 10 such that it is sandwiched between endless belt 15 and drum 12. A textile material 20 (or wrapper) for

example of cotton which is made wet, can also be fed to apparatus 10 such that it is sandwiched between fabric 19 and the

surface of drum 12. The entry and exit apertures 17 and 18 for vessel 14 each include a sealing arrangement 24 (which may

include rollers) to minimise the leakage of compressed air from vessel 14. Suitable seals are known in the art and are thus not

further described herein.

Drum 12 includes a suitable arrangement (shown substantially by block 22) for heating its surface up to, for example, a

temperature of about 180.degree. C. It will be evident from FIG. 1 that a clockwise rotation of drum 12 will convey fabric 19 and

the wet cotton wrapper 20 through a treatment zone between the heated outer facing surface of drum 12 and the inner facing

surface of belt 15, which zone extends around the drum starting from about where the belt 15 contacts the surface of drum 12

after entry into vessel 14 and finishing about where it leaves the drum just prior to its exit from vessel 14.

Belt 15 may be made of an impermeable silicone material. As a fabric 19 is transported through the vessel 14, it is compressed

between belt 15 and drum 12 sufficiently to ensure the fabric retains its flatness, that is, to ensure that a desirable fabric finish

is maintained. This compression is provided by tension in belt 15 assisted by the force which the pressurised atmosphere within

vessel 14 exerts on the belt. That is, it is to be understood that belt 15 is tensioned, but this tensioning and the consequentiallateral pressure that the belt exerts on the fabric 19 is relatively low in that the belt's tension is required only to exert reasonable

lateral pressure to maintain the fabric flatness. Simultaneously, the interaction between the heated surface of drum 12 and wet

surface of wrapper 20 causes a rapid evaporative/condensative heat transfer process to occur which establishes a saturated

(or superheated, depending oil the temperature and the amount of moisture) steam atmosphere within the treatment zone.

Use of a wet cotton wrapper 20, which gives a saturated regain to the fabric, is not essential and as an alternative wrapper 20

can be omitted and the surface of the fabric 19 which contacts the heated surface of drum 12 can be moistened prior to

entering the apparatus 10. For example, free water can be applied to the surface of fabric 19 by a spray (not shown).

Alternatively, steam may be introduced into the treatment zone via perforations in the drum 12, or from a steam chamber

arrangement provided within the pressure vessel 14 via a permeable belt.



FIGS. 2, 3 and 4 are schematic cross-sectional representations (for explaining the operation of the invention) of similar

apparatus to that shown in FIG. 1, that is, in these views the conveying members movement is in a direction that is normal to

the page. Features in these views which correspond with the above described features in FIG. 1 have been accorded the same

reference numerals. Thus, FIG. 2 shows a heated drum 12 around which an endless belt 15 travels with a fabric 19 sandwiched

between the outer facing surface of the drum 12 and the inner facing surface of the belt 15. Pressure vessel 14 is schematically

represented by an enclosing broken line. It contains compressed air at room temperature.

The FIG. 2 embodiment is similar to the FIG. 1 embodiment except it does not employ a moisture laden cotton wrapper 20.

The endless belt 15 of FIG. 2 is impermeable and it presses the fabric 19 against the outerfacing surface of heated drum 12. In

this embodiment steam is generated by the evaporation of moisture in or on the fabric 19. The, pressurized environment within

vessel 14 means that belt 15 need not be a high tensile belt to seal the treatment zone, which zone is defined between the

facing surfaces of the belt 15 and drum 12. Thus it is not critical that the belt 15 seal against the facing surface of drum 12

laterally of the edges of the fabric 19 (see references 26). For example if the air pressure within vessel 14 is at 300 kPa (3

atmospheres) (gauge), belt 15 only needs to exert an additional pressure of, for example, 50 kPa (0.5 atm) to form a

pressurized enclosure for sealing the fabric and set it flat. The steam generated in this enclosure is actually subjected to a

gauge pressure of 350 kPa (3.5 atm) and therefore the corresponding saturated steam temperature therein is 148.degree. C.

(from Steam Tables), provided that the temperature of the heated drum 12 is above this temperature. For a wool fabric 19,

provided there is sufficient moisture in the fabric init ially, preferably 25% regain or higher, a high level of permanent set can be

imparted to the wool fabric in less than 30 secs. The fabric 19 can also be wetted prior to entering pressure vessel 14 for

improving the level of permanent set imparted, however a drying cycle may be required immediately afterward to stabilize the

surface finish.

In the embodiment shown by FIG. 3, belt 15 is permeable and a moisture laden cotton wrapper 20 (as in FIG. 1) is sandwichedbetween the outer facing surface of heated drum 12 and the fabric 19. A micro-climate of saturated steam at high temperature,

as required to net the wool fibers of fabric 19, can still exist in the treatment zone despite the permeability of belt 15 because of

the surrounding region of compressed air in vessel 14. Steam that leaks through the permeable belt 15 will mix with the

compressed air and eventually condense on the cold surface of pressure vessel 14 and ca be drained away. Because the belt

15 is permeable, there will be an insignificant "cushioning effect" by the saturated steam atmosphere within the treatment zone,

thus the belt 15 is only required to exert sufficient mechanical pressure to flat set the fabric 19. The evaporation of water held

by cotton wrapper 20 is controlled by the drum 12 temperature while the saturated steam temperature can be controlled by

controlling the compressed air pressure within vessel 14. For example, if the air pressure of the compressed air in vessel 14 is

300 kPa (3 atm gauge pressure), the saturated steam temperature in the treatment zone will be about 144.degree. C. (from

Steam Tables) provided that the temperature of the heated drum is set at about 10.degree. C. higher to facilitate a high rate of

evaporation. The amount of steam required is controlled by the wetness of cotton wrapper 20. Once all the water has

evaporated, the heated drum 12 can act as a medium to dry the treated fabric 19, giving it a stable surface finish as it emerges

from the pressure vessel 14. Thus the need for an additional drying cycle as required in other processes can be eliminated.

In the embodiment shown by FIG. 4, belt 15 is permeable and the cylindrical surface of drum 12 contains perforations 28.

Saturated steam from a supply 30 is fed to a chamber 32 within drum 12 and forced therefrom through perforations 28, fabric

19 and permeable belt 15.

In the FIGS. 3 and 4 embodiments, the lateral pressure exerted on the fabric 19 can be controlled more exactly than that in the

FIG. 2 embodiment because of the permeability of belt 15, thus it is expected that these embodiments would give a more

consistent treatment.

In experiments that the applicant has conducted on two fabrics, one plain weave and one twill fabric, both preconditioned at

25% initial regain, permanent set values of up to 71% have been achieved.

Generally, it is thought that the level of permanent set increases with increasing air pressure inside vessel 4, higher

temperature of drum 12 and longer treatment/resident times. However high drum temperatures and longer treatment times can

result in yellowing of wool fabrics. The applicant is continuing to conduct experiments to optimise all controlling variables,

including the initial regain of fabric which was not changed in the above mentioned experiments. Generally, the applicant's

experiments have shown that to obtain permanent set values of 60-85% within a treatment time of about 15 seconds, for fabrics

at 18-25% regain, the absolute pressure of the saturated steam needs to be 450-600 kPa (4.5-6 atm.).

The invention also includes the option of preheating belt 15 prior to its wrapping around a fabric 19 on drum 12 to modify the

finish on the adjacent surface of fabric 19. It is also within the scope of the invention that the belt 15 tension be varied between

batches of fabric to manipulate the setting process and hence modify fabric properties such as handle, smoothness and hygral

expansion.

It will be appreciated that the apparatus depicted in FIG. 1 generally provides for the fabric relaxation/setting stage of a

pressure decatising process and that the fabric 19 may then be subjected to a fabric stabilising stage. Suitable fabric

stabilisation operations are known in the art. However it is possible to include in the one apparatus both a relaxation/setting and

a stabilising stage as in the apparatus depicted by FIGS. 5 and 6.



FIG. 5 shows a further embodiment wherein a heated perforated drum 40 is mounted for rotation via shaft 42 within a pressure

vessel 44. The outer surface of drum 40 may be covered with a permeable textile material 41. An endless permeable belt 46 is

arranged around a series of rollers 48 such that it t ravels into vessel 44 through an entry aperture 50, around 80-90% of the

circumferential surface of drum 40 and then out an exit aperture 52. Sealing arrangements are provided for the entry and exit

apertures as is known. A fabric 54 is conveyed through vessel 44 sandwiched between material 41 on drum 40 and endless

belt 46. A tensioning arrangement 56 for endless belt 46 is located within pressure vessel 44 rather than outside the vessel

because this allows better control of the belt tension.

A steam chamber 58 is arranged over a portion of the circumferential surface of drum 40 within vessel 44 and may include aseal arrangement 60 at the interface between its longitudinal and circumferentially extending walls and the belt 46. The belt

46/fabric 54/material 41/drum 40 interface completes the steam chamber. The belt 46/fabric 54/material 41/drum 40 interface is

permeable such that saturated steam can pass therethrough. Steam chamber 58 is arranged relative to drum 40 such that the

fabric 54 is subjected to saturated steam soon after it contacts drum 40 and such that the steaming is terminated whilst the

fabric still has a distance to travel on the drum which is sufficient for cooling and drying it. Thus this apparatus eliminates the

need for an additional drying (stabilisation) cycle.

In operation of the apparatus shown in FIG. 5, compressed air at approximately 450 kPa (4.5 atm) gauge is maintained in

pressure vessel 44 and a compressed air atmosphere of approximately 400 kPa (4 atm) gauge is maintained within drum 40,

with the pressure within steam chamber 58 at approximately 450 kPa (4.5 atm) gauge. The seals 60 are not critical because of

the surrounding compressed air at 450 kPa. Air needs to be continually pumped into vessel 44 to maintain the pressure therein

depending on the flow rate through the belt 46/fabric 54/material 41/drum 40 interface and losses through apertures 50 and 52.

FIG. 6 shows a modification of the apparatus of FIG. 5 (similar features in the two figures have been accorded the same

reference numeral) wherein a cylindrical chamber 62 is provided interiorly of the drum 40. Chamber 62 is fixed, ie. it isstationary and drum 40 rotates around it. The cylindrical wall of drum 40 is closely adjacent the cylindrical wall of chamber 62.

Chamber 62 includes internal partitions 64 for providing at least two compartments 66 and 68 therein, and the outer

circumferential surface of chamber 62 is perforated. A cold shield 70 (in place of steam chamber 58) is provided over the belt

46/fabric 54/material 41/drum 40 interface opposite and in alignment with compartment 66 of chamber 62. In operation of this

apparatus, compressed air at approximately 400 kPa (gauge) is maintained in vessel 44 whilst compressed air at approximately

450 kPa (gauge) is maintained in compartment 68 and saturated steam at approximately 450 kPa gauge is maintained in

compartment 66. Thus the fabric 54 undergoes a relaxation/setting stage as it proceeds over compartment 66 and a

stabilisation stage (cooling and drying) as it proceeds over compartment 68. Cold shield 70, which may be water cooled, is for

trapping moisture in the steam through condensation, which condensation can be drained away.

In relation to application of the invention for continuously setting staple fibers, wherein the staple fibers are contained in an

assembly of fibers such as a sliver, roving, strand, yarn or the like, an apparatus for performing the method may be similar to

that disclosed in the applicant's Australian Patent No. 645026 (61669/90), which wag published internationally as No. WO

91102835, with the addition of an enclosing pressure vessel for containing compressed air for controlling the temperature of the

steaming treatment. The disclosure of this patent is to be taken as incorporated herein by this cross-reference. In this

apparatus the fibers in an assembly of fibers are constrained by impart ing false twist to the assembly. Also, any of the above

described embodiments of FIGS. 1 to 6 may be used for handling an assembly of fibers in place of a fabric 19.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically

described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall

within the spirit and scope of the following claims.

Dec at is Ing

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