Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
  • D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
  • D06M11/38—Oxides or hydroxides of elements of Groups 1 or 11 of the Periodic System

Definitions

• viscose Although viscose has certain inherent advantages as a fabric fibre 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 minimise loss of strength when wet and in order to minimise shrinkage it is common to apply a textile resin. However the amount that is applied has to be such that the resultant fabric loses some of the desirable properties of viscose and instead becomes rather harsh, especially when wet, and the easy care properties are still not entirely satisfactory.
• viscose Another disadvantage of viscose is that it has very poor dye receptivity, probably because when the viscose fibre is contacted with a dye the fibre swells and so reduces the capillary action that is necessary for reception of dye. Accordingly it is not possible to dye viscose fabrics by conventional continuous dyeing techniques.
• Viscose is soluble in alkali and since many of the conventional treatments for giving easy care properties require alkali treatment it would be expected that they would result in destruction or damage of the fibres.
• cellulosic fabrics are considered by many users to possess properties that make them preferable to synthetic fabrics for wear in hot humid conditions a disadvantage of many such fabrics is that they become less soft with increasing moisture. Accordingly although they may be very comfortable under moderate conditions of temperature and humidity at high humidity the softness of the fabric has been reduced, thus making the humidity more noticeable to the wearer.
• 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 permanently shrunk by at least 5%.
• the fabric may be formed solely of viscose fibres or it may be formed of viscose fibres together with other fibres, generally in an amount of not more : than 50% by weight.
• These other fibres may be synthetic fibres but preferably are natural fibres, most preferably cotton or linen.
• Preferred fabrics contain from 50 to 90% viscose and 10 to 40% cotton or linen.
• the fabric When the fabric is formed of a blend of viscose fibres and other fibres the fabric may be formed of yarns consisting of viscose and yarns consisting of the other fibres but more usually is formed of 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 W080/00463.
• 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 cellulosic 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-link, hydroxy groups in the cellulose.
• 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. They generally are acidic, for instance inorganic or organic acids such as citric or succinic acid or acidic salts such as magnesium chloride.
• non-phase separation curing agents for instance a triethylene glycol citric acid or other citric acid water soluble polyester
• the cross-linking agent and activator are generally applied from an aqueous solution containing, for instance 10 to 30% of the cross-linking agent and 0.5 to 5% of the activator.
• the pick up may be, for example, 50 to 80% by weight 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.
• 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 latter being preferred.
• Typical concentrations of caustic soda or other reagent are 10 to 40%, especially 20 to 30%, by weight giving about 60 o Tw.
• Treatment preferably comprises impregnation e.g. by immersion in a 3 bowl trough mangle at a temperature below 30°C, preferably 0 to 10°C. Impregnation of caustic soda between 0-10°C is the preferred method.
• the success of the invention resides partly upon the fact that the initial cross-linking provides an appropriate degree of restraint but a that the viscose swells and the fibres permanently shrink as a result of the mercerisation. Without the cross-linking step, the fibres would dissolve during the mercerisation. It seems that the cross-linking provides restraint such that unique changes occur in the structure of the fibres during the mercerisation. It can be considered that the fibres pass through a thermoplastic state. Whatever the precise mechanism, it is a fact that appropriate combination of cross-linking followed by mercerisation and permanent shrinkage results in a surprising improvement in the wet crease resistance of the fibres.
• the preferred cross-linking agents are cyclic alkylene urea derivatives, for instance dihydroxy dimethylol cyclic methylene or ethylene urea and it is convenient to express the degree of cross-linking by reference to the add-on of such cross-linking agents to the fabric.
• the degree of cross-linking should be below 20% add-on since satisfactory results are not usually obtainable with higher values, unless the cross-linking agent decomposes partially during mercerisation.
• the cross-linking should be above 3% 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 4% are particularly desirable when the fabric has a wide warp spacing since it is then possible to make a stretch fabric.
• add-ons are from 5 to 20%, especially 5 to 15%. Best results are generally obtained with add-ons of from 8 to 13%, most preferably about 10%.
• add-ons are from 5 to 20%, especially 5 to 15%. Best results are generally obtained with add-ons of from 8 to 13%, most preferably about 10%.
• the cross-linking agent is formaldehyde, either introduced as such or liberated from a formaldehyde donor, then the equivalent amounts of add-on will be very much less, due to the lower molecular weight of formaldehyde.
• the conditions of mercerisation are such that the weft viscose fibres have a final shrinkage of at least 50% and preferably at least 75% of their potential shrinkage and the warp fibres have a shrinkage of at least 25% and preferably at least 33% of their potential shrinkage.
• the duration of the mercerisation should be selected to be sufficiently long to achieve the desired degree of shrinkage.
• the mercerisation may be conducted while no tension 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 tension and some reduction in the warp 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 remain unchanged or may be reduced slightly as a result of stentering the fabric out to a controlled width, which still results in a final shrinkage of at least 5%.
• 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, for instance by pulling it on a stenter.
• the tension by which-it is held must be such as to permit the desired final shrinkage to occur.
• the shrinkage that remains in the weft fibres is at least 10%, generally 10 to 25t 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, 15%, usually 5 to 12% and most preferably 8 to 10%.
• a fabric consisting or containing a large proportion of viscose fibres will generally have a wet crease angle of about 90°, and this angle is not substantially changed by the cross-linking.
• 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 the mercerised and shrunk products of the invention have good wet crease resistance.
• the dry crease resistance of the initial fabric is generally around 100 and this may increase slightly, for instance to 110°, by the cross-linking. However the 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 generally less with phase separation catalysts than with non-phase separation curing agents as discussed above.
• the wet and dry crease angles mentioned herein are the angles measured by the Shirley Crease Angle test. Higher values indicate better properties.
• fabrics obtainable by cross-linking and mercerisation as described above have good handle 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 resistance and it has surprisingly been found that this can be achieved without damaging the other properties of the fabric by applying a textile resin or by further cross-linking the mercerised product.
• Suitable textile resins are known for the treatment of cotton and may be applied in a similar manner to obtain an add-on of 2 to 10%, preferably 3 to 7% and most preferably around 5%.
• the dry crease resistance is improved by subjecting the fabric to a final cross-linking, generally using about half the amount of cross-linking agent used for the initial cross-linking, so that the solids add-on is preferably about to 10%, e.g 3 to 7% most preferably around 5%.
• This reduced add-on may be achieved using more dilute solutions of the cross-linking agent.
• the cross-linking materials and process may be selected from the process and materials discussed above for use in the initial stage.
• the final dry crease angle will be 110 to 140°C. Best results are generally obtained using a non-phase 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 also good dry crease resistance.
• a particular advantage of the invention is that the fabrics also can have a unique property in that the fabric becomes softer with increasing humidity.
• a separate aspect of the invention resides in a novel fabric that contains viscose fibres and which is characterised in that the fibres have been cross-linked and the fabric becomes softer with increasing humidity.
• Another advantage of the invention is that it results in the viscose fibres being much more easily dyeable than normal.
• viscose fabrics processed in accordance with the invention can be subjected to continuous dyeing techniques which normally are suitable for use on, for instance-, cotton but not viscose.
• the process of the invention results in it being possible to obtain the same depth of shade but using only half the amount of dyestuff:
• a fabric may be 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 20% w/v solution of dihydroxy dimethylol cyclic 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 may be about 70% and the dry add-on about 10% by weight.
• the fabric may then be dried on the stenter, heated to a temperature of about 170°C for 2 minutes, washed and dried.
• the fabric may then be passed into and pulled out of a bath of caustic soda solution of about 30% and may be drawn out of the bath and partially pulled 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.
• 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%.
• no tension is applied in the weft direction, with the result that the weft fibres shrink, and the weft dimension.reduces, by about 25%.
• the rinsing weft tension is applied on the stenter to an amount such that the final shrinkage is about 20%, based on the original width of the 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 humidity.
• Example 1 The process of Example 1 may be repeated using magnesium chloride as the activator instead of the described polyester.
• the final washed fabric will be found, to have wet crease resistance as good as in Example 1 and dry crease resistance rather better than in Example 1.
• Example 1 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 15% by weight.
• the mercerisation may then be conducted by impregnating the fabric, after cross-linking, with 30% caustic soda solution at about 5°C and then leaving the impregnated fabric in a J box for about 15 minutes before partially pulling it back to width and rinsing and drying it.
• Example 1 or Example 2 may be repeated except that after washing the mercerised fabric the fabric may then be impregnated with a 10% w/v solution of dihydroxy dimethyl cyclic ethylene urea- activated with 1% w/v triethylene glycol citric acid polyester.
• the impregnation may be conducted while the mercerised fabric is held on a stenter and it may be then dried, heated to about 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%.
• Example 1 or Example 2 may be repeated.except that after washing the mercerised fabric the fabric may be impregnated with a solution of urea formaldehyde resin, having a molar ratio urea:formaldehyde of 1:4 and ammonium dihydrogen phosphate activator at a concentration to give a solids add-on of about 5% 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 wet crease and dry crease resistance and softness.
• the fabrics treated and shrunk in the process of the invention may be used to make shaped goods, eg clothes, by conventional methods, while in their permanent shrunk state.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Artificial Filaments (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26276092

Family Applications (1)

Country Status (10)

Cited By (6)

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Citations (6)

Family Cites Families (1)

• 1981
  • 1981-07-01 JP JP56502228A patent/JPS57501189A/ja active Pending
  • 1981-07-01 BR BR8108671A patent/BR8108671A/pt unknown
  • 1981-07-01 WO PCT/GB1981/000120 patent/WO1982000164A1/fr active Application Filing
  • 1981-07-01 HU HU812296A patent/HU184471B/hu unknown
  • 1981-07-01 EP EP81303002A patent/EP0044172A1/fr not_active Ceased
  • 1981-07-02 GR GR65412A patent/GR74368B/el unknown
  • 1981-07-02 ES ES503628A patent/ES503628A0/es active Granted
  • 1981-07-02 PT PT73309A patent/PT73309B/pt unknown
  • 1981-07-03 PL PL23202681A patent/PL232026A1/xx unknown
• 1982
  • 1982-03-02 NO NO820648A patent/NO820648L/no unknown

Patent Citations (7)

Non-Patent Citations (2)

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