TREATMENT OF FABRICS

Abstract: Fibrous cellulosic material is treated by applying an aqueous solution including a polycarboxylic acid cross-linking agent and an organic or inorganic sulphonic or sulfinic acid, particularly p-toluene sulphonic acid, methane sulphonic acid and dodecyl benzene sulphonic acid, or salt particularly alkali metal, ammonium or alkaline earth metal salts, as an esterification catalyst, drying the fabric and heating it to promote cross-linking esterification of the polycarboxylic acid and the cellulose of the fibrous cellulosic material to give fabric with improved wrinkle and/or crease and/or shrink resistance and/or smooth drying properties. The method has the advantage that it does not use formaldehyde derivatives and thus the operation of the method and treated materials do not release formaldehyde during manufacture or use and the catalysts do not contain or use phosphorus containing compounds.

Description: Treatment of Fabrics This invention relates to 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 containing cellulosic fibres or yarns. 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 shrink resistance and/or smooth drying properties to cellulosic fabrics, particularly cotton textiles, are known. The treated fabrics and 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 fabrics by a finishing treatment with resinous compositions. The most commonly used resins for such finishing are based on formaldehyde derivatives 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 during manufacture, storage and/or use of cellulose, particularly 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 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 boric acid or derivatives as crosslinking catalyst. Welch ef 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 materials. 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 containing effluents can promote algal growth and/or eutrophication of downstream water bodies such as streams and lakes. The present invention is based on the discovery that certain sulphur containing acids, particularly sulphonic and/or sulfinic acids, and their alkali metal salts at lower concentration show accelerating effect on esterification 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 compounds, but can give adequately rapid esterification 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 cellulosic material is treated with a polycarboxylic acid in the presence of a sulphonic and/or sulfinic acid curing catalyst at elevated temperature. The process can be carried out by impregnating the material with a solution containing 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 an organic or inorganic sulphonic or sulfinic acids or a salt as an esterification catalyst, b drying the textile material fabric 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 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 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 treatment of the fabric 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 fabric is less likely to be wrinkled or creased after being worn or after a laundering operation than it would if it had not been so treated. 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 acids are known from the literature. Suitable polycarboxylic acids for use in the method of this invention include aliphatic, including open chain and alicyciic, 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 molecule. 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 ethyienic double bond, it is very desirable that it is positioned α,β- to a carboxylic acid group; such an aliphatic acid may include a hydroxyl group on a carbon atom also 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, methyimaieic (citraconic) acid, citric acid, itaconic 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 degree of cross linking desired, the proportion of cellulosic fibres in fabric being treated and the solubility of the crosslinking agent. 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. The curing catalysts used in this invention are organic or inorganic sulphonic or sulfinic acids or their salts. Suitable catalysts include inorganic sulphonic acids i.e. compounds including the group S0 3 H (or S0 2 OH), particularly haiosulphonic and amidosulphonic acids, particularly those of the general formula: XS0 2 OH where X is Cl, F or NH 2 , respectively chlorosulphonic and fluorosulphonic acids and amidosulphonic acid (taurine). Suitable organic sulphonic acids typically have the general formula: RS0 2 OH where R is an organic group, particularly an alkyl or cycioalkyl group, an unsaturated straight or branched chain hydrocarbyl, particularly alkenyl group, or an unsaturated cyclic or arene group. Particularly active and effective curing catalysts of this invention include the alkane sulphonic acids and 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 trifluoromethanesulphonic acid. Other useful curing catalysts include arene and alkyl arene sulphonic acids such as benzene, p-hydroxybenzene, p-toluene and dodecylbenzene sulphonic acids, naphthalene-1- and napthalene-2-suiphonic acids and 1,3-benzene and 2,6-naphthalene disulphonic acids and benzene sulphinic acid. The sulphonic or sulfinic 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 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 the effect of the drying and heating_steps. We 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. Generally sulphonic acids are strong enough acids that they will be present as the free acid (often largely dissociated) in aqueous solution at pH about 3. The amount of catalyst used will 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 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 treatment is typically carried out by first impregnating the cellulosic or cellulosic containing textile 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, e.g. 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 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 the dry weight of the untreated textile. We have confirmed the presence of cellulose ester carbonyl groups in material treated according to 5 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 " (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 10 1735 cm " . The treatment solution containing the crosslinking agent and the curing catalyst forms part of the 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 ■|5 solution, and at least one organic or inorganic sulphonic or sulfinic acids or a salt as an 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 20 residues of at least in one polycarboxylic acid cellulose crosslinking agent esterified to hydroxylic sites in the cellulose and residues of at least one organic or inorganic sulphonic or sulfinic acids or a salt esterification catalyst. In these aspects of the invention particularly desirable features are as described for the method of 25 the invention. 30 The following Examples illustrate the invention. All parts and percentage are by weight unless otherwise stated. Materials BTCA 1 ,2,3,4-butanetetracarboxylic acid OMAi oiigo-maleic acid made using benzoyl peroxide as the polymerisation initiator OMAii oligo-maleic acid made using hydrogen peroxide/acetic anhydride as the polymerisation initiator MSA methane sulphonic acid Surf Commercial proprietary domestic detergent ex Hindustan lever Test Methods Wrinkle recovery angles (WRA) were determined by ATCC Test Method 66-1990; Wrinkle recovery of fabrics: Recovery angle method. The wrinkle resistance of woven textiles is represented by the wrinkle recovery angles; the greater the WRA the greater the wrinkle resistance of the fabric. Results are reported in degrees. Exa ple 1 This Example illustrates the use of MSA (Examples 1a, 1b and 1c) as a curing catalyst for the durable press finishing of cotton fabric using BTCA. Cotton cloth test pieces (10 inches square; ca. 25x25 cm;) were thoroughly wetted by immersion in a treatment bath containing an aqueous solution (80 ml) of BTCA (5 g; 6.25%w/v) and MSA (concentration given in Table 1 ) 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 dry cloth. The test pieces were stretched on a rack and dried in an air forced draft oven at 85°C for 5 minutes. The dried test pieces were then treated in an air draft oven at the temperatures and for the times shown in Table 1 below, in which amounts of BTCA and MSA are expressed as weight % based on dry fabric weight. The treated specimens were rinsed for 5 minutes with 1% Surf solution, rinsed with water and air dried and the WRA's) were measured. The WRA results are included in Table 1 below. Table 1 Example 2 This Example compares MSA ( Example 2) and sodium hypophosphite (comparative Example C2) as curing catalysts for durable press finishing of cotton fabric with BTCA. The general procedure of Example 1 was followed using the appropriate catalysts and the results are set out in Table 2 below. Table 2 Example 3 This Example compares MSA (Examples 3a, 3b and 3c) and sodium hypophosphite (comparative Example C3) as curing catalysts for durable press finishing of cotton fabric with OMA as the crosslinking agent, Examples 3a and 3b used OMAi and Examples 3c and 3C OMAii. The general procedure of Example 1 was followed using the appropriate catalysts in the treatment bath in the concentrations stated in Table 3 below and the results including WRA data are set out in Table 3 below. Table 3 Example 3 Cotton cloth specimens were prepared by the general procedure of Example 1 using 5% BTCA as the treatment resin and MSA as the curing catalyst at levels of 5% and 1 % by weight on the dry fabric. The specimens were heat treated at 180°C for 90 seconds. FT-IR spectroscopic examination of both specimens, with particular attention to the frequency range 1750 to 1720 cm " , showed absoφtions at 1728 cm attributed to the presence of crosslinked ester groups.

Claims: We Claim 1 A method of treating fibrous cellulosic textile material which method comprises: a applying to the cellulosic textile material an aqueous solution including at least one polycarboxylic acid and an organic or inorganic sulphonic or sulfinic acids or a salt as an esterification catalyst, and b drying the fabric and heating it to promote crosslinking esterification of the polycarboxylic acid and the cellulose of the cellulosic textile material. 2 A method as claimed in claim 1 wherein the sulfonic or sulfinic acid is one ore more of alkane and/or cycloalkane and/or alkene sulphonic acids, unsaturated cyclic and/or arene sulphonic acids and/or heterocyclic sulphonic acids. 3 A method as claimed in claim 2 wherein the catalyst is methane sulphonic acid and/or benzene sulphinic acid. 4 A method as claimed in any one of claims 1 to 3 wherein the polycarboxylic acid includes at least two carboxylic acid groups are separated by 2 or 3 carbon atoms. 5 A method as claimed in any one of claims 1 to 4 wherein the polycarboxylic acid crosslinking agent is one or more of maleic acid, methylmaleic acid, citric acid, itaconic acid, 1,2,3-propanetricarboxyiic acid, 1 ,2,3,4-butanetetracarboxylic acid, all c/s-1,2,3,4-cycio- pentanetetracarboxylic acid, oxydisuccinic acid, thiodisuccinic acid, oligo- and/or poly-maleic acid and/or anhydride, benzene hexacarboxylic acid and trimellitic acid. 6 A method as claimed in claim 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 methane sulphonic acid and/or benzene sulfinic acid. 7 A method as claimed in any one of claims 1 to 6 wherein the amount of polycarboxylic acid crosslinking agent used is from 1 to 10% by weight based on the dry fabric weight. 8 A method as claimed in claim 7 wherein the amount of polycarboxylic acid used is from about 2 to about 7% by weight based on the dry fabric weight. 9 A method as claimed in any one of claims 1 to 8 wherein the amount of hydroxycarboxylic acid catalyst used is from 1 to 100% by weight of the polycarboxylic acid crosslinking agent. 10 A method as claimed in claim 9 wherein the amount of hydroxycarboxylic acid used is from 2 to 30% by weight of the polycarboxylic acid crosslinking agent. 11 A method as claimed in claim 10 wherein the amount of hydroxycarboxylic acid used is from 5 5 to 20% by weight of the polycarboxylic acid crosslinking agent. 12 A method as claimed in any one of claims 1 to 11 wherein the heating step is carried out at a temperature of from 150 to 240°C. 10 13 A method as claimed in claim 13 wherein the temperature is from 160 to 200°C. 14 A method as claimed in any one of claims 1 to 13 wherein the heating step is carried out for a time of from 5 seconds to 30 minutes. 15 15 A method as claimed in claim 14 wherein the time is from 1 to 5 minutes. 20 25 30 35

Inventors: ARUMUGASWAMY RAMIAH, DIKE SUNEEL YESHWANT, HAJARNIS UMED DATTATRAY, ARUMUGASWAMY, RAMIAH, DIKE, SUNEEL, YESHWANT, HAJARNIS, UMED, DATTATRAY
Applicants: ARUMUGASWAMY RAMIAH, DIKE SUNEEL YESHWANT, HAJARNIS UMED DATTATRAY, ICI PLC, ARUMUGASWAMY, RAMIAH, DIKE, SUNEEL, YESHWANT, HAJARNIS, UMED, DATTATRAY, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1998
Main classification: D06M13
IPC codes: D06M13