NZ331058A - Treatment of fabrics with a process comprising polycarboxylic acid - Google Patents

Abstract

A method of imparting wrinkle and/or crease and/or shrink resistance and/or smooth drying properties to fabrics made from cellulosic fibres or yarns or blends thereof, the method not involving the use of formaldehyde, formaldehyde derivatives or phosphorus containing compounds. More particularly, the method involves a treatment of fibrous cellulosic textile material comprising; a) applying to the cellulosic textile material an aqueous solution including at least one polycarboxylic acid, as described in the above formula wherein: R3 is a CH2 group, or a direct bond n is from 1 to 3 each R4 is independently a C1 to C4 alkyl group m is 0, 1 or 2 and/or a salt thereof. as a crosslinking agent for the cellulose and one or more aromatic mono-carboxylic hydroxy acids or a salt as an esterification catalyst. b) Drying the textile material and heating it to promote crosslinking esterification of the polycarboxylic acid and the cellulose of the cellulosic textile material.

Description

New Zealand Paient Spedficaiion for Paient Number 331 053 Intellectual Property Office of New Zealand IP Summary Report Page 1 of 1 Date 18 January 2000 Time 11 18 27 (iprip02 2 00 16) (51) Classification C07C57/32, C07C59/245, C07C59/265, C07C65/03, C07D307/60, D06M1S/05 IPC Edition IPC Status 70 Accepted Client Ref P394133 THS/ghn 331058 Version number 6 IP type Patent Convention (22) NZ Filing date 21 July 1998 (30) Priority Data (31) 981362CAL (32) 21 July 1997 (33) IN (30) Priority Data (31) 98 9802032 (32) 31 January 1998 (33) GB (30) Priority Data (31) 98 9802031 (32) 21 July 1998 (33) GB (71) Applicant IMPERIAL CHEMICAL INDUSTRIES PLC, Imperial Chemical House, Millbank, London SW1P 3JF, United Kingdom (72) Inventors Dike, Suneel Yeshwant Arumugasmy, Ramiah Hajarnis, Umed Dattatray Contact A J PARK & SON, 6th Floor, Huddart Parker Building, Post Office Square, Wellington, NZ Primary Examiners JENNY JEBSON Journal 1448 Date actions completed Application Accepted Next renewal date 18 January 2000 21 July 2002 Office title Treatment of fabrics with a process v-ompnsing polycarboxylic acid (54) Applicant title Treatment of fabrics (57) Abstract Patent 331058 A method of imparting wrinkle and/or crease and/or shrink resistance and/or smooth dryin properties to fabrics made from cellulosic fibres or yarns or blends thereof, the method not involving the use of formaldehyde formaldehyde derivatives or phosphorus containin compounds More particularly, the mpthod involves a treatment of fibrous cellulosic textil material comprising, a) applying to the cellulosic textile material an aqueous solution including at least on polycarboxylic acid as described in the above formula wherein R3 is a CH2 group or a direct bond n is from 1 to 3 each R4 is independently a C, to C„ alky' group m is 0 1 or 2 and/or a salt thereof as a crosslinking agent for the cellulose and one or more aromatic mono-carboxylic hydrox acids or a salt as an esterification catalyst b) Drying the textile material and heating it to promote crosslinking estenfication of th polycarboxylic acid and the cellulose of the cellulosic texti|e material_ ** End of report ** No Date NEW ZEALAND-PATENTS ACT, 1953 COMPLETE SPECIFICATION TREATMENT OF FABRICS We, IMPERIAL CHEMICAL INDUSTRIES PLC, a British company, of Imperial Chemical House, Millbank, London SW1P 3JF, United Kingdom, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described m and by the following statement (followed by page - la -) -1a- This invention relates to a method of imparting wrinkle and/or crease and/or shrink resistance and/or smooth drying properties to fabncs made from cellulosic fibres or yarns or blends containing 5 cellulosic fibres or yams More particularly it relates to such a method of treatment which does not involve the use of formaldehyde or formaldehyde derivatives or phosphorus containing compounds Many commercial processes for imparting wrinkle, crease and/or shnnk resistance and/or smooth drying properties to cellulosic fabrics, particularly cotton textiles, are known The treated fabncs and 10 garments made from them retain their dimensions and smooth appearance in use and also during machine wash and tumble dry processes Commercially, such properties can be imparted to cellulosic fabncs by a finishing treatment with resinous compositions The most commonly used resins for such finishing are based on 15 formaldehyde denvatives such as formaldehyde-urea or substituted urea addition products such as DMEU and DMDHEU Such resins are believed to function by promoting crosslinking of the cellulose in the fabric thereby imparting the desired properties In recent years, efforts have been made to develop crosslinking agents which do not include formaldehyde or its derivatives to remove the possible evolution of formaldehyde dunng manufacture, storage and/or use of cellulose, particularly 20 cotton fabrics, treated with formaldehyde addition products Non-formaldehyde crosslinking agents which have been suggested previously include polycarboxylic acids as disclosed by Gaghiardi and Shipee, American Dyestuff Reporter 52, 300 (1963) Rowland et al, Textile Research Journal 37, 393 (1967), disclosed the use of partially neutralized 25 polycarboxylic acids with base prior to the application to the fabric in a pad, dry and heat cure treatment, elaborated US Patent 3526048 Canadian Patent No 2097483 describes rapid esterification and crosslinking of fibrous cellulose in textile form using bone acid or derivatives as crosslinking catalyst Welch et al in US Patents 4975209,4820307, 4936865 and 5221285 disclose the use of alkali metal salts of phosphorus containing acids, particularly sodium hypophosphite as crosslinking esterification catalysts in the treatment of cellulosic matenals The use of sodium hypophosphite has several disadvantages it is expensive, relatively high levels are needed in practice and it tends to cause shade changes in fabrics dyed with sulphur dyes or certain reactive dyes In addition, phosphorus 35 containing effluents can promote algal growth and/or eutrophication of downstream water bodies such as streams and lakes , ... J3J058 The present invention is based on the discovery that certain hydroxycarboxylic acids and/or their salts, particularly alkali metal salts at lower concentration show accelerating effect on estenfication and crosslinking of cellulose by polycarboxylic acids The use of such catalysts can enable the provision of a treatment method that uses neither formaldehyde derivatives or phosphorus 5 compounds, but can give adequately rapid estenfication and crosslinking of cellulosic in fibres to provide effective wrinkle, crease or shrink resistance or smooth drying properties to materials made from such cellulosic fibres Thus, in this invention fibrous celluiosic material is treated with a polycarboxylic acid in the presence of a hydroxycarboxylic acid curing catalyst at elevated temperature The process can be earned out by impregnating the material with a solution containing 10 the polycarboxylic acid and the curing catalyst followed by heat treatment to produce esterification and crosslinking of the cellulose with the polycarboxylic acid The present invention accordingly provides, a method of treating fibrous cellulosic textile material which comprises a applying to the cellulosic textile material an aqueous solution including at least one polycarboxylic acid as a crosslinking agent for the cellulose and one or more aromatic mono-carboxylic hydroxy acids or a salt as an esterification catalyst, b drying the textile material and heating it to promote crosslinking esterification of the polycarboxylic acid and the cellulose of the cellulosic textile material In referring to the material as being "cellulosic", we mean that the major part of the fibre forming components of the material is cellulose Thus, the term includes purely cellulosic materials such as cotton and cellulose-rich blends particularly cellulose-rich polyester blends, such as polycotton materials Typically, the material contains from 30 to 100% of cellulosic fibres Typical cellulosic 25 fibre materials which can be included in fabrics treated according to this inventions include cotton, flax, rayon, jute, hemp and ramie it can also be a synthetic cellulosic fibre material such as rayon, particularly viscose rayon or solvent derived rayon commonly called lyocell fibre The cellulosic material can be a blend of fibres of cellulosic materials with non-cellulosic materials and in particular includes blends of cellulosic fibres, particularly cotton, with polyester, particularly polyethylene 30 terephthalate polymer or related copolymers The textile can be a woven (including knitted) or non-woven textile, but as crease resistance is particularly important in clothing, the textile will usually be a clothing textile material The term "formaldehyde free" means that the process does not release formaldehyde during the 35 treatment of the fabnc with the resin or during subsequent manufacture of garments or their use including washing and wearing The term "wrinkle or crease resistance" means that a treated fabnc The invention uses polycarboxylic acids as cellulose crosslinking agents to improve the wrinkle resistance, shrinkage resistance and smooth drying properties of cellulosic fibre containing textile without the use of formaldehyde or agents that release formaldehyde Some such polycarboxylic 5 acids are known from the literature Suitable polycarboxylic acids for use in the method of this invention include aliphatic, including open chain and alicyclic, polycarboxylic acids, and aromatic polycarboxylic acids Desirably the polycarboxylic acid includes at least 3, particularly at least 4 and often more carboxylic acid groups per molecuie Particularly suitable aliphatic polycarboxylic acids include acids in which at least two carboxylic acid groups are separated by 2 or 3, more usually 2, carbon atoms and desirably where the polycarboxylic acid includes a plurality of such arranged pairs of carboxylic acid groups Where such an aliphatic acid includes an ethylenic double bond, it is very desirable that it is positioned a,(3- to a carboxylic acid group, such an aliphatic acid may include a hydroxyl group on a carbon atom also 15 carrying a carboxylic acid group, and further the aliphatic chain or ring may include one or more oxygen and/or sulphur atoms Suitable aromatic acids include those where at least two carboxylic acid groups are attached to adjacent aromatic ring carbon atoms Examples of suitable aliphatic polycarboxylic acids include maleic acid, methylmaleic (citraconic) 20 acid, citric acid, itacornc acid, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid (commonly known as BTCA), all c/s-1,2,3,4-cyclopentanetetracarboxylic acid, oxydisuccinic acid, thiodisuccinic acid, oligo- and/or poly-maleic acid and/or anhydride (as described in GB 2295404 A and WO 96/26314 A and abbreviated "OMA") and suitable aromatic polycarboxylic acids include benzene hexacarboxylic acid and trimellitic acid The amount of crosslinking agent used will typically be from 1 to 10%, particularly from about 2 to about 7%, by weight based on the dry fabric weight The particular concentration of crosslinking agent used in the treating solution will depend upon the decree of cross linking desired, the proportion of cellulosic fibres in fabric being treated and the solubility of the crosslinking agent 30 Typically, the concentration is from about 1 to 20%, more usually 2 to 10% particularly from 0 5 to 7 and especially about 5%, by weight of the solution - 4 - _ ^ The curing catalyst used in this invention is one or more aromatic mono-carbo\ylic hydroxy acids Suitable compounds include mono-carboxylic hydroxy acids in which at least one of the carboxyi and hydroxyl groups is directly attached to the aromatic ring Desirably, the carboxyl group and at least one hydroxyl group are directly attached to the aromatic ring The ring may also carry inert substituents such as one or more C1 to C4 alkyl group(s), but desirably, not more than two such groups are attached to the aromatic ring Particular aromatic acids are of the formula (II) (HO)nv D 4 ' " m /X o >— R —COOH (II) Vx" where R3 is a CH2 group, or, and desirably, a direct bond, n is from 1 to 3, particularly 1 or 2, 4 each R is independently a C-, to C4 alkyl group, and m is 0,1 or 2 Among aromatic acids, those where the carboxylic acid group and a hydroxyl group are directly attached to the aromatic ring and are positioned substituted ortho- to each other on the ring are particularly useful Very desirable such 'ortho-acids' are those of the formula (III) (HO)n-^VOH Q ;^COOH (111) where p4 -■ " m m and R4 are independently as defined for formula (II) and n' is 0 or 1 Examples include 3-hydroxybenzoic acid, 4-hydroxy- benzoic acid and 2-hydroxyphenylacetic acid and examples of suitable ortho-acids include 2-hydroxybenzoic acid (salicylic acid), 2,4-dihydroxybenzoic acid (b-recorcylic acid), 2,4-dihydroxy- 5-methylbenzoic acid (orcinylic acid) 30 and the cresotic acids, especially 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid and 2-hydroxy-5-methylbenzoic acid The hydroxycarboxylic acid catalyst can be used as the free acid or as a salt, particularly an alkali metal ammonium or alkaline earth metal salt, or a mixture of the free acid and a salt or salt(s) The 35 salt forming cations are particularly of potassium, sodium, ammonium, magnesium, calcium or a mixture of these cations It is not clear whether the free acid form or the salt form of the curing catalyst is the more active component of the catalyst The form present will depend on the acidity of the solution used for the treatment of the textile and tlre'^ffto^Wheidrylogrirp^^ling steps We j CFNZ Li 1 4 CCC 1299 R E^C FIV E D I have found that the textile is advantageously treated using a moderately acidic solution, typically having a pH of from 2 to 6, usually not more than 4 5, more usually from 2 5 to 4 and especially about 3 Under such conditions, the curing catalyst may be present as the neutral free acid, as acid anions or a mixture depending on the acidity of the catalyst Aromatic 2-hydroxy- carboxylic acids 5 (ortho-acids) typically have acidities in aqueous solution such that both the neutral free acid and the acid anions are present at significant concentrations (relative to he overall concentration of the catalyst) at pH values of about 3 In making up treatment solutions, it will often be convenient to start by dissolving a readily water 10 soluble metal or ammonium salt and subsequently adjusting the pH of the solution rather than to try to dissolve what may be a sparingly soluble free acid at the use pH directly The amount of hydroxy aromatic acid catalyst used will typically be from 1 to 100%, more usually 1 to 50%, desirably 2 to 30% and especially 5 to 20%, by weight of the polycarboxylic acid crosslinking 15 agent Expressed as a percentage based on (the dry weight of) the material being treated, the amount will typically be from 0 1 to 10%, more usually from 0 2 to 3%, particularly 0 5 to 2% by weight The concentration used in the treatment solution is typically from 0 1 to 10%, more usually from 0 2 to 5%, particularly from 0 3 to 2%, by weight of the solution The action of the hydroxy aromatic acid catalysts used in this invention seems to go beyond the effect that might be expected of a simple catalyst We do not know why this may be, but suspect that because the hydroxy aromatic acid catalysts have at least two potentially reactive sites, they may be acting to form further cross links by reacting with the cellulose and/or with the polycarboxylic acids used as cellulose crosslinking agents The precise mechanism by which the effect arises is not 25 critical to the invention The catalysts used in this invention can be used alone or in combination with other catalytic materials In particular they can be used in combination with organic or inorganic sulphonic or sulfinic acids or salts In such combinations, suitable organic or inorganic sulphonic or sulfinic acids or their salts include inorganic sulphonic acids i e compounds including the group S03H (or SOzOH), particularly halosuiphonic and amidosulphonic acids, particularly those of the general formula XS02OH where X is CI, F or NH2, respectively chlorosulphonic and fluorosulphonic acids and amidosulphonic acid (taurine), and organic sulphonic acids which typically have the general formula RS02OH where R is an organic group, particularly an alkyl or cycloalkyl group, an unsaturated straight or branched chain hydrocarbyl, particularly alkenyl group, or an unsaturated cyclic or arene group especially suitable organic catalysts inlcude the alkane sulphonic acids and ^31 £* o their alkali metal salts e g methane, ethane, propane, butane, pentane and hexane sulphonic acids, camphor sulphonic acid, isethionic acid (2-hydroxyethane sulphonic acid), methane- di-sulphonic acid and tnfluoromethanesulphonic acid Other useful curing catalysts include arene and alkyl arene sulphonic acids such as benzene, p-hydroxybenzene, p-toluene and dodecylbenzene sulphonic 5 acids, naphthalene-1- and napthalene-2-sulphonic acids and 1,3-benzene and 2,6-naphthalene disulphonic acids and benzene sulphinic acid Sulphonic or sulfinic acid catalysts can be used as the free acids or as salts, particularly an alkali metal, ammonium or alkaline earth metal salts, or a mixture of free acid and salt(s) The salt forming 10 cations ate particularly of potassium, sodium, ammonium, magnesium, calcium or a mixture of these cations It is not clear whether the free acid form or the salt form of this type of catalyst is the more active form The form present will depend on the acidity of the solution used for the treatment of the textile and the effect of the drying and heating steps At the moderately acid conditions typically used in this invention, it is likely that any sulphonic or sulfinic acid catalysts used will be present mainly as 15 the (electrically) neutral free acid When the catalyst system includes a sulphonic or sulfinic acid catalyst, the amount of this additional catalyst used wilt typically be from 10 to 200%, more usually 25 to 150%, desirably 50 to 120%, by weight of the polycarboxylic acid crosslinking agent Expressed as a percentage based on the (dry 20 weight of the) textile being treated, the amount will typically be from 1 to 30%, more usually from 2 to 20%, particularly 2 5 to 10% by weight The concentration used in the treatment solution is typically from 0 1 to 20%, more usually from 0 2 to 10%, particularly from 0 5 to 7%, by weight of the solution The use of sulphonic or sulfinic acids as a reaction catalyst in the preparation of fibrous cellulosic 25 textile materials having improved crease and wrinkle resistance is the subject of New Zealand Patent Specification No 331057 The treatment is typically carried out by first impregnating the cellulosic or cellulosic containing textile 30 materials with an aqueous treating solution containing the crosslinking agent and the curing catalyst, and removing excess liquid e g using wringers, with these steps being repeated, if necessary, to obtain the desired liquid pick up The material is then dried to remove the solvent and then cured, eg in an oven, typically at about 150 to 240°C, usually from 160 to 200°C for a time of from 5 seconds to 30 minutes, usually 1 to 5 minutes to promote the esterification and crosslinking of the 35 cellulose by the polycarboxylic acid Typically the pick up of treatment solution is from 30 to 120%, more usually from 50 to 100%, particularly about 80% of tt^Tdry .weight of the untreated textile rMLatL^L rWLfiTY'office! OF NZ I J * CCC !3s9 J RECEIVFD I i rr - / 1 v We have confirmed thp presence of cellulose ester carbonyi groups in cellulosic textile material treated according to the invention by FT-IR (Fourier transform infra red) spectroscopy The absorption band of the carbonyls of cellulose esters in infra red spectra has been reported and in the range of 1720 to 1750 cm"1 (Zhbankov, P G , "Infrared spectra of cellulose and its derivatives", Consultant Bureau, New York, 1968, pp 315-316) Our observations show an absorption peak at about 1720 to 1735 cm"1 The treatment solution containing the crosslinking agent and the curing catalyst forms part of the 10 invention which accordingly specifically includes an aqueous solution of at least in one polycarboxylic acid cellulose crosslinking agent, particularly at a concentration of from 1 to 20% by weight of the solution and at least one aromatic mono-carboxylic hydroxy acid esterification catalyst, particularly at a concentration of from 0 2 to 10% oy weight of the solution The invention further includes an aqueous solution of at least in one polycarboxylic acid cellulose crosslinking 15 agent particularly at a concentration of from 1 to 20% by weight of the solution, at least one aromatic mono-carboxylic hydroxy acid estenfication catalyst particularly at a concentration of from 0 2 to 10% by weight of the solution and at least one organic or inorganic sulphonic or sulfinic acids or a salt esterification catalyst particularly at a concentration of from 0 2 to 10% by weight of the solution The invention further includes cloth treated by the method of the invention and in particular a cellulosic textile material, which may be woven (including knitted) or non-woven, which carries residues of at least in one polycarboxylic acid cellulose crosslinking agent esterified to hydroxylic sites in the cellulose and residues of at least one aiomatic mono-carboxylic hydroxy acid 25 esterification catalyst In this aspect the invention also includes a cellulosic textile material, which may be woven (including knitted) or non-woven, which carries residues of at least in one polycarboxylic acid cellulose crosslinking agent esterified to hydroxylic sites in the cellulose residues of at least one aiomatic mono-caiboxylic hydroxy acid estenfication catalyst (which may be bound chemically to the textile or to lesidues of at least in one polycarboxylic acid 30 cellulose crosslinking agent) and at least one hydroxycarboxylic acid esterification catalyst, particularly at a concentration ot from 0 2 to 10% by weight of the solution In these aspects of the invention particularly desirable features are as described for the method of the invention CPW 50522 The following Examples illustrate the invention All parts and percentage ate by weight unless otherwise stated Materials BTCA 1,2,3,4-butanetetracarboxylic acid OMA ohgo-maleic acid Surf Commercial proprietary domestic detergent ex Hindustan Lever Test Methods 10 Wrinkle recovery angles (WRA) were determined by ATCC Test Method 66-1990 Wrinkle recovery of fabncs R* ^ve^y angle method The wrinkle resistance of woven textiles is represented by the winkle recovery angles, the greater the WRA the greater the wrinkle resistance of the fabnc Results are reported in degrees Example 1 This Example illustrates the use of salicylic acid (introduced as sodium salicylate) as a curing catalyst for the durable press finishing of cotton fabric using BTCA Cotton cloth test pieces (10 inches square, ca 25x25 cm,)' Qre thoroughly wetted by immersion in a treatment bath containing an aqueous solution (80 ml) of BTCA (5 g) and sodium salicylate (0 5 g) as curing catalyst at a pH adjusted to 3 The wetted cloth was passed between the rolls of a wringer and the process repeated twice to give an overall pick up 80% by weight of the treatment solution based on the dry weight of the untreated cloth The test pieces were stretched on a rack and dried in 25 an air forced draft oven at 85°C for 5 minutes The dried test pieces were then treated in an air draft oven at 180°C for 2 minutes The measured WRA was 278° Treated test pieces had a WRA of 256° after immersion for 5 minutes with 1% Surf solution, followed by rinsing with water and air drying 30 Example 1C Example 1 was repeated, but substituting sodium benzoate (5 g) for the sodium salicylate used in Example 1 and gave a WRA (before washing) of 261° Example 2 Example 1 was repeated but substituting oligomaleic acid (OMA) for the BTCA used in Example 1 and gave a WRA (before washing) of 255° CPW 50522 Example 3 Example 1 was repeated, but substituting sodium 3-hydroxybenzoate (1 g) for the sodium salicylate used in Example 1 and gave a WRA (before washing) of 276° 5 Example 4 Example 1 was repeated, but substituting sodium 4-hydroxybenzoate (1 g) for the sodium salicylate used in Example 1 and gave a WRA (before washing) of 276° Example 5 Example 1 was repeated, but substituting sodium 2-hydroxyphenylacetate (1 g) for the sodium salicylate used in Example 1 and gave a WRA (before washing) of 274° -I0- ;- --A

Claims (5)

WHAT WE CLAIM IS , - c/ .:

1 A method of treating fibrous cellulosic textile material which comprises a applying to the cellulosic textile material an aqueous solution including at least one polycarboxylic acid as a crosslinking agent for the cellulose and one or more aromatic mono-carboxylic hydroxy acids or a salt as an estenfication catalyst, b drying the textile matenal and heating it to promote crosslinking estenfication of the polycarboxylic acid and the cellulose of the cellulosic textile matenal

2 A method as claimed in claim 1 wherein the estenfication catalyst is a mono-carboxylic hydroxy acid of the formula (II) ^ iV- r3-cooh ("> R4 k- m where R3 is a CH2 group, or a direct bond, n is from 1 to 3, each R4 is independently a C1 to C4 alkyl group, and m is 0, 1 or 2, and/or a salt thereof 3 A method as claimed in claim 2 wherein the catalyst is an aromatic hydroxycarboxylic acid of the formula (III) OH (111) ^ ; V-COOH (R4 )nT X^1-y/ where m and R4 are independently as defined for formula (II) in claim 2 and n' is 0 or 1 and/or a salt thereof 4 A method as claimed in either claim 2 or claim 3 wherein the catalyst is one or more of

3-hydroxybenzoic acid,

4-hydroxybenzoic acid, 2-hydroxyphenylacetic acid, 2-hydroxybenzon acid, 2,4-dihydroxybenzoic acid, 2,4-dihydroxy-

5-methylbenzoic acid, 2-hydroxy-3-methyl-benzoic acid, 2-hydroxy-4-methylbenzoic acid and 2-hydroxy-5-methyibenzoic acid and/or a salt thereof _ ^ I^Or'ERTY OF fJZ 14 Lr~ mi 33j05S A method as claimed in any one of claims 1 to 4 wherein the catalyst additionally *J includes one or more organic or inorganic sulphonic or sulfinic acids or salts;A method as claimed in claim 5 wherein the catalyst additionally includes one or more alkane sulphonic acids or alkali metal salts;A method as claimed in ary one of claims 1 to 6 wherein the polycarboxylic acid crosslinking agent includes at least two carboxylic acid groups separated by 2 or 3 carbon atoms;A method as claimed in any one of claims 1 to 7 wherein the polycarboxylic acid is one or more of maleic acid, methylmaleic acid, citnc acid, itaconic acid, 1,2,3-propanetncarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, al! c/s-1,2,3,4-cyclopentanetetracarboxylic acid, oxydisuccinic acid, thiodisuccinic acid, oligo- and/or poly-maleic acid and/or anhydnde, benzene hexacarboxylic acid and tnmellitic acid;A method as claimed in cla'm 1 wherein the polycarboxylic acid is 1,2,3,4-butane tetra-carboxylic acid and/or oligo- and/or poly-maleic acid and the catalyst is 2-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid (|}-recorcylic acid), 2,4-dihydroxy- 5-methylbenzoic acid, 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, 2-hydroxy-5-methyl-benzoic acid or a mixture or a salt thereof;A method as claimed in any one of claims 1 to 9 wherein the amount of polycarboxylic acid crosslinking agent used is from 1 to 10% by weight based on the dry fabric weight;A method as claimed in claim 10 wherein the amount of polycarboxylic acid used is from 2 to 7% by weight based on the dry fabnc weight;A method as claimed in any one ot claims l to 11 wherein the amount of mono-carboxylic hydroxy acid catalyst used is fiom l to 100% by weight of the polycarboKyhc acid crosslinking agent;A method as claimed in claim 12 wherein the amount of mono-carboxylic hydroxy acid used is from 2 to 30% bv weight ot the polycarboxylic acid crosslinking agent;A method as claimed in claim 13 wlietein the amount of mono-carbo\ylic hydroxy acid used is fioin 5 to 20% by weight of the polycarboxylic acid crosslinking agent;A method as claimed in any one of claims 1 to 14 wherein the heating step is carried out at a temperature of from 150 to 240°C I ''^^LECTUAL PROPERTY OfFiCE;OF NZ;i * e:c C99 - 12- A method as claimed in claim 15 wherein the temperature is from 160 to 200°C A method as claimed in any one of claims 1 to 16 wherein the heating step is carried out for a time of from 5 seconds to 30 minutes A method as claimed in claim 17 wherein the time is from 1 to 5 minutes An aqueous treatment solution of at least one polycarboxylic acid cellulose crosslinking agent, at a concentration of from 1 to 20% by weight of the solution, and at least one aromatic mono-carboxylic hydroxy acid or a salt as an esterification catalyst, at a concentration of from 0 2 to 10% by weight of the solution A cellulosic textile matenal which carries residues of at least in one polycarboxylic acid cellulose crosslinking agent estenfied to hydroxylic sites in the cellulose and residues of at least one at least one aromatic mono-carboxylic hydroxy acid or a salt A method as claimed in claim 1 substantially as hereinbefore described with reference to any one of Examples 1 to 5 A cellulose textile material whenevei treated by a method as claimed in any one of claims 1 to 18 25 30 35 16 17 5 18 19 10 20 15 21 20 22