WO1982000164A1

WO1982000164A1 - Fibrous product containing viscose

Info

Publication number: WO1982000164A1
Application number: PCT/GB1981/000120
Authority: WO
Inventors: Licensing Co Ltd Lintrend
Original assignee: Sloan F
Priority date: 1980-07-03
Filing date: 1981-07-01
Publication date: 1982-01-21
Also published as: JPS57501189A; PL232026A1; HU184471B; PT73309B; PT73309A; BR8108671A; NO820648L; GR74368B; ES503628A0; ES8204010A1; EP0044172A1

Abstract

A fabric containing viscose fibres is subjected to cross-linking followed by mercerisation and then generally further cross-linking. It is possible to obtain products having good dyeability soft handle and good wet and dry crease resistance.

Description

FIBROUS PRODUCT CONTAINING VISCOSE

The United States Application des ignated in this appl ication is a continuation-in-part o £ United

States Application Serial No. 237, 874 tiie entire disclosure o £ whic is completely incorporated here hy reference.

It is common practice to impart easy care properties (for instance wet and / or dry creas e resistance), to fabrics formed of cotton fiber, or blends containing cotton fiber with, for instance, polyester fiber.

S Such methods involve the use of inter alia textile

res ins or cellulos ic cross-linking agents .In PCT

Patent Specification W080 / i00463 'a process is described for imparting easy care properties to linen products, optionally mixed with voscose.

0 It would be very desirable to be able to make-a wide "range of easy care products containing viscose but it has not previously" been possible to achieve th s by any convenient commercial methods.

, 'Although viscose has certain inherent

S advantages as a fabric fiber it also suffers from

serious disadvantages. Thus an untreated viscose fabric will not have satisfactory easy care properties, and

for instance will readily crease .In an attempt at

improving the easy care properties and in order to

0 minimise loss o £ strength, when wet and in order to

minimise shrinkage it is common to -D ly a textil e

-resin. However the amount that is appl ied has to to

be such that the resultant fabric los es some of the

des irab le properties of viscose and instead becomes

5 rather harsh, especially when wet, and the easy care

properties are still not entirely satisfactory.

Another disadvantage of viscose is that

it has very poor dye receptivity, probab ly because when the vi scose fiber is contacted with a dye the f ibre swells and so reduces the capillary action that is

necessary for reception of dye.

not possible to dye viscose fabrics by conventional

continuous dyeing techniques.

Viscose is soluble in- alkali and s ince many o £ the conventional treatments for giving easy care

properties require alkali treatment it would be

expected that they would result in destruction or damage o £ the fibres.

It has been alleged, in German Patent Specification 1173428, that good dry .and wet resistance and soft hand on fabrics of native or regenerated

cellulose can be obtained by treating the fabrics with a compound that evolves formaldehyde when heated followed by treatment with a solution containing 2 to 61 alkali and a glycol softener.In practice however this method does not give very satisfactory results when applied

to viscose containing fabrics,

In British Patent Specification No. 10344S3 a process is described of forming a bulked fabric "by

cross -linking viscose rayon fiber and then using this

fiber to form a fabric which is then impregnated with

caustic soda and then pulled back to full width.It is also mentioned that the cross-linking can be conducted on the fabric itself, but this is not free and

in fact it seems probable that t e desired bulk effect would not be .achieved if the cross-linking was conducted on the fabric instead o £ the free fiber.

The process has not been adopted commercially for the treatment of fabric and, prior to the present

Invention, there has been no known commercial process

for making a fabric including substantial amounts of

viscose xilares and that has an acceptable combination

of dry and wet crease resistance and softness.

Although cellulos ic fabrics are cons idered

by many users to possess properties that make them

preferred to synthetic fabrics for wear in hot humid

, CM? I conditions a disadvantage of many such fabrics is that they become less soft with increasing moisture.

According although they may be very comfortable under moderate conditions of temperature and humidity at

5 high humidity the softness of the fabric has been

reduced, thus making the humidity more noticeable to the wearer.

It has been our object to devise a method of forming a fabric including viscose fibres and which 10 has a good combination of wet crease resistance and softness and preferably also dry crease resistance.

In the invention a fabric that includes viscose fibres, generally in an amount of at least 301 by weight of the fibres in the fabric, is impregnated with, an

S initial cross-linking agent and an activator for this,

the agent is cured, the fabric is then mercerised while allowing shrinkage o £ viscose fibres, and the viscose fibres in the fabric are allowed to remain permanently shrunk by at least 5%.

0 The fabric may be formed solely o £ viscose

fibres or it may ¾e formed of viscose fibres together with other fibres, generally in an amount o £ no.t more i than 50% by weight.

'' synthetic fibers but preferably are natural fibers,

S most preferably cotton or linen.Preferred fabrics

contain from SO to 90¾ viscose and 10 to 40% cotton or lirien. ¾ ·

When the fabric is formed of a blend of

viscose fibres and other fibres the fabric may be formed0 of yarns consisting of viscose and yarns consisting o £

the other fibres but more usually is formed o £ yarns each comprising a blend of viscose and the other fibres.

Suitable methods of forming appropriate linen, blends are known and reference may be made to, for instance, PCT

Publication 080/00463.

Any material capable of cross-linking the cellulosic molecules of the viscose fibres to the

desired extent may be used.Formaldehyde donors may be used but preferably the initial cross -linking is

achieved by impregnation with a conventional eel lulos ic cross-linking agent and an activator.

This cross-linking agent is a bi- or poly-functional reagent that will react with, and thus bridge and cross-l ink, hydroxy groups in the cellulos e.

Typical bi- or poly-functional compounds that serve as cross -linking agents are alcohols, triazones, aldehydes such as glyoxal, and methylol urea derivatives that will react with, cellulose in preference to undergoing self polymerisation, such, as dimethylol cyclic

methylene or ethylene or other alkylene urea.

Activators suitable for use with such cross-linking agents are well known and are generally referred to as catalysts or curing agents.

acidic, for instance inorganic or organic acids such

as citric or succinic acid or acidic salts such, as

magnesium chloride .Every, ins ead o £ using

phase separation catalysts such, as these, non-phase

separation curing agents (for instance a txiethyTene ''

glycol citric acid or other citric acid water soluble

polyester) are used.

The cross -linking agent and activator are

generally applied from an aqueous solution containing, for instance 10 to 30% o £ the cross -linking agent and

0.5 to 5% of the activator.The pick up may be, for

example, SO to 801 by height of the solution.

Curing of the cross-linking system may be

achieved by, for instance, heating at 120 to 220 ° C for

0.5 to 5 minutes.

Known mercerising reagents and temperatures may be used for the mercerising step in the invention.

Suitable reagents are strong ammonia, cuprammonium

solutions and other alkaline solutions generally of

alkaline earth metal hydroxides, for instance calcium

hydroxide or alkali metal hydroxides, generally sodium

hydroxide, the l atter being preferred.Typical

concentrations of caustic soda or other reagent are 10

CMPI to 40¾, especially 20 to 30¾, by we ight g iving about

60 ° Tw.Treatment preferably compris es impregnat i on e.g. by immers ion in a 3 owl trough mangle at a

temperature below 30 ° C, preferab ly 0 to 10 ° C.

S Impregnation.o £ caustic soda between 0-10 ° C is the

preferred method. This is obtained by refrigerating

the caustic soda and circulating the l iquor in the

trough for the impregnating mangle .The contact

with alkali is generally relatively quick, for instance 10 I to 30 minutes and usually 1 to 10 minutes ^ whereupon

the fibrous material is washed with water to eliminate the allcali or other mercerising reagent.

It seems that the success of the invention resides partly upon the fact that the initial cross- IS linking provides an appropriate degree of restraint

¾ut that the viscose swells and the fibres--^ r permanently shrink as a result of the mercerisation. Without the cross-linking step, the fibres would dissolve during

the mercerisatio'n.It seems that the cross-linking

20 provides restraint such that unique changes occur.

structure of the fibres during the mercerisation- It can be considered that the fibres pass through a t ermoplastic state.Whatever the precise mechanism,

T 'it is a fact that appropriate combination of cross-linking 25 followed by mercerisation and permanent shrinlcage results in a surprising improvement in the wet crease resistance of the fibres.

In order to obtain good resul ts a s significant amount of swel ling must occur.

30 insufficient cross-linking the degree o £ swelling will

be so much that, after drying the fabric, the fibres

will be very brittle and hard.If the degree o £ cross- lmJ iiig is too much then the f bric becomes very rigid and inadequate swel ling occurs.However higher than ϋ normal degrees of cross-linking can be tol erated if the

cross-l inking agent is one that is degraded by the

mercerising conditions, since the mercerisat ion wil l then result init ially in reduction of the degree o £ cross-linking and then in the ~ -des ired swel ling and shr inkage.

The preferred cross-linking agents are

cyclic alkylene urea derivatives, for instance d ihydroxy dime thy lol cyclic methyl ene or ethylene urea and it is

S convenient to express the degree o £ cross-linking by

reference to the add-on o £ such tross-linking agents

to the fabric.In general the degree of cross-linking should be below 201 add-on s ince satisfactory results are not usually obtainable with higher values,

10 unless the cross-linking agent decompos es partially

during mercerisation- Generally the CTOS S linking should be above 31 add-on, since with lower amounts

the degree of restraint is so small that very high

shrinkage will occur.Low add-ons such as 3 or

15 Ai are particularly desirable when, the fabric has a

wide warp spacing since it is then possible to make

a stretch fabric.For more usual purposes however suitable add-ons are from S to 20%, especially S to

.15 1 .Best results are generally obtained with add-ons 20 of from S to 13%, most preferably about 101 .When a

different type o £ cross -linlcing agent is used then

different, but equivalent, amounts o £ add-on will be::

required. For instance if the cross-linking agent

is formaldehyde, either introduced as such or liberated 25 from a formaldehyde donor, then the equivalent amounts

of add-on will be very much less, due to the lower

molecular weight of formaldehyde.

For any particular degree of cross -linking

there will be a potential shrinkage obtainable by the 30 fabric during prolonged mercerisation and preferably

the conditions o £ mercerisation are such, that the weft viscose fibres have a final shrinkage of at .least SOI and preferably at least 75 ¾ o £ their potential shrinkage and the warp fibres have a shrinkage of at l east 251

i and preferably at least 33% of their potential shrinkage.

For instance the duration of the jnercerisation should be sel expected to be suffici ently long to achieve the des ired degree of shrinkage .With the lower degrees of

O PI cross-linking (for instance equ ival ent to 15 ¾ add-on or less) it is usually sufficient for mercerisation to be conducted for not more than 10 or IS minutes but

with higher degrees of cross-linking, for instance I S to 20¾ add-on, longer periods up to 30 minutes or even more may be required.- '

The mercerisation may be conducted while

no tens ion is applied in the warp or weft, for instance while the fabric is allowed to remain in a relaxed

state in a trough, and the fabric may then be pulled lengthwise (i.e. in the warp direction) to the next

processing stage (for instance rinsing and drying),

This pulling will result in some warp tens ion and some reduction in the waT shrinkage, which, previously will preferably have been the full shrinkage attainable.

The weft shrinkage, which also will preferably have been the maximum shrinkage attainable, may be allowed to

rem in unchanged or may be reduced s lightly as a result o £ stentering the fabric out to a controlled width,

which still results in a final shrinkage o £ at least '

51.Another way of achieving the mercerisation

is to conduct the mercerisation while restricting the fabric against some shrinkage in the warp direction and optionally also in the weft direction, or instance by pulling it on a stenter:-.The tension by which-it is held must be such as to permit the des ired final

shrinkage to occur. *

Preferably the shrinkage that remains in the weft fibres is at least 10¾, generally 10 to 25% and

most preferably 15 to 20% .The shrinkage that

remains in the warp may be similar but lower shrinkages can be tolerated and may be up to, for instance, 15¾, usually S to 12% and most preferably 8 to 10%.

With most fabric constructions the degree

of shrinkage can be observed s imply by measuring the

reduction in the width and length of the fabric .However with, very tight weaves the weave its elf may prevent

reduction in the width, or length of the fabric even 01.1PI though the fibres within the fabric will have shrunk.

Accordingly it should be understood that the percentage shrinkage values that are quoted are normally the

values obtainable by measuring the width and length, of

5 th.e fabric but that if this is a very tight weave then

they are the values that would be obtainable by a more loosely woven fabric t.reated under the same conditions.

A fabric consisting or containing a large

proportion of viscose fibers will generally have a wet

10 crease angle o £ about 90 °,. And this angle is not

substantially changed by the cross -linking .However the wet crease angle after the mercerisation and permanent shrinkage in the invention can easily be increased to

120 ° or more, for instance as much as 140 ° .Accordingly 15 the mercerised and shrunk products of the invention have

good wet crease resistance.

The dr crease resistance of the initial

fabric is generally around 100 ° and this may increase slightly, for Instance to 110 ^σ _Λ by the cross-linking.

20 However t e mercerisation will generally result in a- reduction of this, for instance back to a value of about 100 .The loss in dry crease angle is general ly less with phase separation catalysts than with non-phase

, 'Separation curing agents as discussed above.

5 The wet and dry crease angles mentioned here are the angles measured by the Shirley Crease Angle test.Higher values indicate ', "better properties.

Although fabrics obtainable by cross-linking and mercerisation as described above iiave good handle

0 and wet crease resistance, and are thus suitable for use

as, for instance, table cloths or upholstery fabrics, it is desirable to improve their dry crease res instance and it has surpris ingly been found tliat this can be

achieved without damaging the other properties o £ the

5 fabric ¾y applying a textile res in or by further cross- linking the mercerised product.

resins are l nown for the treatment of cotton and may

be applied in a s imilar manner to obtain an add-on o £

OMPI 2 to 10¾, preferably 3 to 7% and most preferably around 5%.

However however the dry crease res istance is improved by subj ecting the fabric to a final cross-S linking, general ly using about half the amount of cross- linking agent used for the initial cross-linking, so that the solids add-on is preferably about 2 to 10¾, e.g 3 to 71 most preferably around S% .This reduced add-on may be

achieved us ng more dilute solutions of the cross-10 linking agent .The cross-linking materials and process

may be selected from the process and materials discussed above for use in the initial stage.Typically the final dry- crease angle will be 110 to 140 ° C.Best results are generally obtained using a non-phase

15 separation curing agent, for instance a polyester as

mentioned above, and this has the particular advantage that it gives a fabric having better abrasion resistance.

Fabrics made by the invention have a soft handle and good wet crease resistance, and optionally

20 also good dry CTea.se resistance .A particular,

advantage o £ the invention is that the fabrics also

can have a unique property in that the f bric becomes softer with increasing humidity. ''

,-Accordingly a separate aspect o £ the invention S resides in a novel fabric that contains viscos e fibres

and which is characterised in that the fibres have been cross-linked and the fabric becomes softer with Increas ing humidity.

Another advantage of. The invention is that

0 it results in the viscose fibres being much more

easily dyeable than normal .Thus viscose f brics

processed in accordance with the invention can be

subj expected to continuous' d ^ ei.ng techniques which normally are suitable for use on, for instance, cotton but not

5 viscose .Typically the process of the invention results in it being possible to obtain the same depth of shade but us ing only half the amount oi dyestuff ½

The following are exampl es of the invention.

C PI Example 1

A f bric may tie formed of yarn formed of a blend of viscose and 25% linen or cotton fibres .The fabric may be impregnated while held on a stenter with

5 201 w / v solution of dihydroxy dimethylol cycl ic

ethylene urea activated with 2% -w / v triethylene glycol citric acid polyester.The acid value of the polyester may be about 190 and the pH of the impregnating solution should be at least 3. 2.The wet pick up of the fabric

10 may be about 701 and the dry add-on a out 10% by weight.

The fabric may then be dried on the stenteT, heated to a temperature o £ about 170 ° C for 2 minutes, washed and

dried.

The fabric may then be passed into and pulled IS out of a bat of caustic soda solution o £ about 301

and may be drawn out of the "bath, and partially.

"back to width, on a stenter while being rinsed with, water.The duration of contact between the caustic soda solution and the viscose fibres may be about 1 to 2 minutes.

20 While the fabric is passing through the "bath and before

it is rinsed with, water (thus terminating the meTcerisation) the tension applied in the length is sufficient to permit the fibres to shrink, and the length, of the, 'fabric to reduce, by about 10%.

5 through, the bath no tension is applied in the weft

direction, with the result that the weft fibres shrink, and the weft dimensioi> ;. reduces, by about 25% .During the rinsing weft tension is applied on the stenter to

an amount such that tlie final shrinkage is about 20¾,

0 based on the original width of t e fabric.

The washed fabric may then be dried.It will have very high, wet crease resistance and may be dyed

"by continuous dyeing techniques and has a soft handle

that becomes softer with, increasing humid ity.

5 Exairole _2

The process of Example 1 may be repeated us ing magnesium chloride as the activator instead of the

described polyester .The final washed fabric will be

• C PI found to have wet crease resistance as good as in Exampl e 1 and dry crease resistance rather better than in Example

Example 3

S The process of Example 1 may be repeated but

using higher concentrations of cross -linking agent, with the result that the add-on is about 151 by weight.

The mercerisation may then be conducted by impregnating the fabric, after cross-linking, with 301 caustic soda.

10 solution at about S ° C and then leaving the impregnated

fabric in a J box for about IS minutes before partially pulling it back to width and rinsing and drying it.

Exam le 4

The process o £ Example 1 or Example 2 may be

IS repeated except that after washing the mercerised fabric

the fabric may then be impregnated with, a 10% / v

solution of dihydroxy dimethyl cyclic ethylene urea-activated wit II w / v triethylene glycol citric acid

polyester.The impregnation may be conducted while

0 the mercerised fabric s held on a s tenter and it *

may ¾e then dried, heated to ab ut 170 ° C for two minutes washed and dried.The final product will have greatly ；

improved dry crease resistance, while retaining the

'wet crease resistance of Examples 1 or 2. The add-on is 5% .5 Example 5

The process of Example 1 or Example 2 may be

repeated except that a ^ f-ter washing the mercerised fabric the fabric may be impregnated with a solution of urea

formaldehyde resin, having a molar ratio urea: formaldehyde0 of 1: 4 and ammonium di ydrogen phosphate activator at

a concentration to give a solids add-on of about S%

and an acidity to give a- pH on the fabric of about 3.2.

The resin may then be cured by heating, followed by

. washing and drying. Again the product has very good

5 wet crease and dry crease resistance and softness.

Tlie fabrics treated and shrunk in th.enrocess of e invention may be used to make shaped goods, eg clothes by conventional methods, while in their permanent shrunk state.

Claims

1 * A process in which, a fabric that includes viscose fibres is impregnated with, an initial cross- linking agent and an activator for this, the agent is cured, the fabric is then mercerised while allowing shrinkage of viscose fibres and the viscose fibres In the fabric are allowed to remain shrunk y at least 5%, the weft fibers preferably being allowed to remain shrunlc by at least 10%.

, A process according to claim 1 in whic the shrinkage of the we £ t dimension o £ the fabric that-remains in the fabric is from 10 to 30%, preferably IS to 25% and the shrinkage o £ the warp dimension of the £ a¾ric that remains in the fabric is from 5 to 30% ₃ preferably 7 to 12%.

3.A process according to claim 1 οτ claim 2 in which, the cross-linking agent is a cyclic alkylene urea cro ss -linking ageiit and the so lids add-on is from 3 to 201 by weight or another cross -linking agent is usea in an amount that gives an equivalent degree of cross -linking.

4.A process according to claim 3 in which, the add-on is S to 13!, Preferably about 10¾.

5.A process according to any preceding claim in which mercerisation is conducted using 10 to 40¾ sodium hydroxide solution.

6.A process according to any preceding claim in which, mercerisation is conducted whil e no tens ion is applied in the warp or weft and the fabric is then pulled in the warp direction and optionally stretched in the weft direction to give the desired final shrinkage or mercerisation is conducted while applying low tension in the warp and optionally also in the weft to give the desired final shrinkage.

7.A process according to any preceding claim in which the shrunk fabric is impregnated with a final cross-linking agent or textile resin and activator, and the cross-linking agent or resin is then cured.

8A process according to claim 7 in which the solids add-on of cross-linking agent or textile resin is from 3 to 7%.

9.A process according to any preceding claim in which, the or each cross-linking-agent is a dihydroxy dimethylol cyclic alkylene urea.

10.A process according to any preceding claim in which the or each, activator is an inorganic acid or salt.

11.A process according * to any o £ claims 1 to 9 in which the or each, activator is a water soluble

polyester formed with citric acid and a glycol.

12.A process according to any preceding claim .in which, the fabric is subsequently subjected to

continuous dyeing.

13.A fabric containing viscose fibres characterised in that the fibres have been cross-linked and

the fabric "becomes sofier with increasing humidity.