GB2295404A - Creaseproofing treatment of fabrics - Google Patents

Abstract

Cellulosic fabrics are treated with an aqueous solution of a maleic acid/anhydride oligomer/polymer (OMA) to improve crease resistance. The treatment does not involve the use of any materials containing formaldehyde or which liberate formaldehyde during processing or subsequent use. Preferred OMAs have molecular weights from 300 to 100000, particularly 300 to 2000. Treatment is usually carried out in conjunction with an esterification catalyst that promotes curing of the OMA onto the cellulosic fabric, which can be wholly cellulosic or a blend, e.g. particularly with polyesters, especially polyethylene terephthalate.

Description

Treatment of Fabrics The present invention relates to a method of treating fabrics or yarns to make them or fabrics made from them more resistant to wrinkles and/or creases and in particular to such a method that does not use compounds derived from formaldehyde or compounds that liberate formaldehyde on treatment of the fabric andlor yam or on subsequent use. The invention relates to such a process for treating cellulosic fabrics and/or yams or blends containing such cellulosic materials.

Methods of treating fabrics to impart wrinkle and/or shrinkage resistance to cotton fabrics are known. Fabrics or garments having cotton, upon such treatment retain their dimensions, smooth appearances and normal shapes while in use and also during machine wash or tumble dry processes. Commercially, such treatment of cellulosic materials is typically carried out by high speed, durable press finishing processes using formaldehyde or formaldehyde addition products, such as those with urea or cyclic urea, carbamate esters or with other amides. The treatment agents are applied to typically cotton textiles with an acid catalyst, and heated to induce crosslinking. These formaldehyde addition products are effective and cheap for such uses.

Unfortunately, they have the serious disadvantage in that they can release formaldehyde during durable press finishing processes, storage of fabric, manufacture of garments and, even during the use of garments by the customer. Formaldehyde vapours are known eye-irritants and skin allergens. Accordingly, there has been a need for durable press finishing processes that do not employ formaldehyde or its addition products. Such conventional processes also have the disadvantage that they require Lewis acid catalysts and high temperature to ensure sufficient and rapid crosslinking of the cellulose. However, Lewis acids at high temperature can cause degradation of cellulose molecules and loss of strength in the finished fabric.

A number of other approaches have been investigated, including formulations based on glyoxaldehyde, acetals, glyoxaldehyde am ides, reactive silicones and polycarboxylic acids having more than two carboxylic acid groups. Thus, Gagliardi and Shipee, in American Dyestuff Reporter 52, pp 300 to 303, (1963) describe the use of polycarboxylic acids with or without catalysts in treatments to impart wrinkle resistance to cotton fabrics. However, although many of the hazards of formaldehyde processes can be avoided, they noted greater fabric strength losses than with formaldehyde based agents.

Rowland et al in Textile Research Journal 37, 933-941 (1967) disclosed a treatment using polycarboxylic acids partially neutralized with sodium carbonate or triethylamine prior to application to the fabric. Good cross linking of cellulose was observed, but a gradual reduction of wrinkle resistance was noted after repeated laundering cycles showing a lack of durability of the finish to alkaline solutions such as laundering detergents. Further, the curing time for fabric finishing was too long to permit high speed, mill-scale production.

A later article by Rowland and Brannan, Textile Research Journal 38, 634-643 (1968), described that cotton fabrics treated as described above were recurable and that creases durable to 5 laundering cycles could be made. US Patent 3526048 describes similar results neutralizing 1 to 50% of the carboxylic acid groups using an alkali metal hydroxide, carbonate, bicarbonate, acetate, phosphate or borate, prior to impregnating the fibrous cellulose with the aqueous polycarboxylic acid and heating to induce cross linking.

US Patent 4975209, to Welch et al, discloses cellulose crosslinking agents which are polycarboxylic acids including aliphatic, alicyclic and aromatic acids which are reported as good crosslinking agents at elevated temperatures in the presence of acidic or weakly basic salts. The treated textiles show good wrinkle resistance and smooth drying properties durable to repeated laundering in alkaline detergents. A further US Patent 4820307 to Welch etna!, also discloses particular types of polycarboxylic acids such as maleic, citric and butanetetracartoxylic acids as cross linking agents in the presence of phosphorus containing catalysts.

US Patent 5042986 describes crosslinking cellulose using cyclic aliphatic polycarboxylic acids having two adjacent carboxyl groups in the transconfiguration. Canadian Patent 2097483 also describes esterification and crosslinking of cellulose in textiles using polycarboxylic acids having more than two carboxylic acids, at elevated temperatures with boric acid or a derivative as crosslinking catalyst.

Two polycarboxylic acids which have evoked industrial interest are 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid. BTCA is one of the most effective crease resist resins and has been marketed by Glo-Tex Inc. as Reactisol DP4, but very expensive and difficult to synthesise (Reactisol DP4. Glo-Tex Chemicals, Inc. P. O. Box 400, Roebuck, S. C. 29376).

We have found that despite the significant steps which have been made in avoiding the disadvantages of formaldehyde based crosslinking agents, much is still left desired. In particular, strength loss and the discoloration of fabrics, especially upon ironing, remain problems.

The present invention is based on our discovery that oligomeric and/or polymeric compounds derived from repeat units of maleic acid andlor an hydride can be used as effective treatment agents for cellulosic materials to improve their crease resistance. We believe that these agents work by crosslinking cellulose molecules in the fabrics by forming ester bonds with hydroxyl groups in the cellulose molecules and for convenience we refer to this mechanism herein. However, the particular chemical mechanism is not itself critical to this invention.

Accordingly, this invention provides a method of treating a fibrous cellulosic textile material, particularly to improve its crease resistance, which method comprises treating the textile with a treatment agent compnsing one or more oligomer(s) andlor polymer(s) of maleic anhydride and/or maleic acid, and thereafter heating the treated textile to cure the treatment agent onto the fibres of the cellulosic textile.

The substrate that is treated in this invention is described as a fibrous cellulosic textile material. By this we mean that the substrate is cellulosic or contains, typically, from 30 to 100% fibres of cellulosic material. Typical cellulosic fibre materials which can be included in fabrics treated according to this inventions include cotton, flax, rayon, jute, hemp and ramie. The cellulosic material can be a blend of fibres of cellulosic materials with noncellulosic 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 present invention includes a novel formaldehyde free method of treating, particularly for imparting wrinkle/crease resistance and smooth drying/shape retention properties to, cellulosic or cellulose containing textiles, particularly containing 30-100% cellulosic materials, which comprises treating the textile material with one or more oligomeric and/or polymeric maleic acid and/or anhydride.

The abbreviation OMA used herein, refers to oligomers and/or polymers of maleic anhydride and/or acid. Generally, the oligomers and polymers used include 3 or more maleic acid and/or anhydride urLits per molecule. Typically the OMA used in the invention will have a molecular weight of from about 300 to 100000, particularly fromabout 300 to 15000 and more particularly 300 to 2000. The term oligomeric maleic acid is sometimes used herein and this term includes oligomeric and polymeric maleic acid and/or anhydride as set out above.

This invention includes a method of treating, particularly for imparting wrinkle/crease resistance and smooth drying/shape retention properties to, cellulosic or cellulosic containing textile materials which comprises treating the textile material with an oligomer andlor polymer of maleic anhydride and/or acid, having 3 or more maleic anhydride or acid units.

More particularly, the process of the invention includes treating the cellulose or cellulose containing textile materials with oligomeric and/or polymeric maleic anhydride and/or acid in the presence of at least one curing catalyst and then heat curing the treated textile to produce esterification and crosslinking of the cellulose with the oligomeric and/or polymeric maleic anhydride and/or acid.

The invention also includes cloth treated by the method of the invention and in particular, a cellulosic textile material, which may be woven (including knotted) or non-woven, which carries residues of oligomeric and/or polymeric maleic acid and/or anhydride esterified to hydroxylic sites in the cellulose.

More particularly, the method of the invention employs an aqueous solution containing about 0.1 to 30% by weight of oligomeric/polymeric maleic acid having average molecular weight from 300 to 100000, preferably from about 300 to about 15000 and more particularly from 300 to 2000. While not being bound to any theory, it is believed that the lower molecular weight oligomeric and/or polymeric maleic acids and/or anhydrides of this invention work best because they can penetrate more easily into the yams of the fabric and, therefore, the lower molecular weight oligomeric and polymeric acids are preferred. This is most surprising since none of the prior art which report the use of polycarboxylic acids point out. even in a remote way, that the oligomer and/or polymer of maleic acid and/or anhydride will behave in such an advantageous fashion.In fact, no prior art known to the applicants suggest the use of a polymer of a polycarboxylic acid as a crosslinking agent, leave alone an oligomer and/or polymer or mixtures therefrom of maleic acid and/or anhydride.

Accordingly, the present invention includes a method of treating a cellulosic or cellulose containing textile material, particularly to produce improved fabric material having wrinkle/crease resistance and smooth drying properties, which method comprises treating the cellulosic textile material with an aqueous solution containing at least one oligomer and/or polymer of maleic acid and/or anhydride having an average molecular weight in the range of from 300 to 100000 and one or more curing catalyst and heating the treated material to cause esterification and crosslinking of said material with said crosslinking agent to produce said improved fabric material.

In particular the oligomeric and/or polymeric maleic acid and/or anhydride includes repeat units:

where each M is independently H, a metal, particularly an alkali metal, or ammonium; and the number of such repeat units in the oligomer and/or polymer averages from about 3 to about 1000 (corresponding to the above described molecular weight ranges).

The particular concentration of oligomeric maleic acid used in the treating solution will depend upon the degree of cross linking desired and on the proportion of cellulosic fibres in fabric being treated. Thus, any convenient concentration of the crosslinking agent may be selected depending upon the degree of crosslinking desired, the preferred range being from about 0.1 to 30% by weight more usually and desirably 0.5 to 20% by weight. The amount of OMA applied to the fabric will typically be from 1 to 10%, particularly from about 2 to about 7%, by weight of OMA based on the dry fabric weight.

The oligomers and polymers of maleic anhydride and/or acid used in this invention can be synthesized by known methods, particularly by free radical polymerisation starting with maleic acid and/or an hydride, for example initiated by peroxides or other similar free radical initiators. Methods of synthesis of the oligomers and polymers use din this invention are described, for example as described in FR 1544728, US 4260724, DE 2405284 A, DE 2732628 A, Makromol Chem., 53, 33; 55:35 (1962), Eur. Polym. J., 12, 883 (1976) and 11 31(1975), Makromol. Chem., 124, 249 (1969), J. Macromol. Sci., Part A, 10, 1017 91976, US 3385834, GB 1073323, DE 2154510 A, US 3457240 and Handbook of polymer synthesis Part A, ed. H R Kricheldorf, Marcel Dekker Inc., Chap. 4, pp 223-310 (1992).

To achieve the best results, the treatment of the fabric will usually be carried out in the presence of a curing catalyst. Accordingly, the treatment solution typically includes a suitable curing catalyst at a concentration usually of about 0.1 to 30% by weight. Amounts outside this range can be used, but will usually be less desirable. In particular, the catalyst is typically used at a level of from 5 to 2%, especially about 10 to about 15%, by weight on the weight of the solid resin used in the treatment of the fabric. The catalyst can be an esterification catalyst for example as is described in more detail below.

Typical catalysts are esterification catalysts. Examples of suitable catalysts include mineral acids such as hydrochloric, sulphuric, fluoroboric, phosphoric, phosphorous and hypophosphorus acids; organic acids such as glycolic, maleic, lactic, citric, tartaric and oxalic acids; metal, particularly alkali metal e.g. sodium, potassium and lithium, salts of the above acids; metallic salts such as magnesium or zinc, chloride, nitrate, sulphate, fluoroborate or fluorosilicate, ammonium chloride or nitrate, aluminium chloride, zirconium oxychloride, sodium and/or potassium bisulphite or bisulphate, alkali metal halides, sodium and/or or potassium phosphite and/or hypophosphite and/or dihydrogen phosphate, disodium or dipotassium hydrogenphosphate, alkali metal salts of polyphosphoric acids such as disodium and/or dipotassium acid pyrophosphate, tetra- sodium and/or potassium pyrophosphate, penta- sodium and/or potassium tripolyphosphate, sodium and/or potassium hexametaphosphate and/or trimetaphosphate or sodium tetrametaphosphate; boron acids such as boric acid and their derivatives such as orthoboric acid, alkali or alkaline earth metal salts of polyboric acids or borate esters of the formula B(OR)3, where R is alkyl or aryl; amine hydrochlorides, such as 2-amino-2-methyl-propanol hydrochloride and similar products. The catalyst compounds can be used alone or in combination.

The curing catalyst used is typically used in the treatment solution in a concentration of from 0.1 to 20% by weight. The precise amount or concentration used will depend on the particular application and we expect that those skilled in the art will not have difficulty in choosing appropriate amounts and/or concentrations.

The invention includes a method of treating a fibrous cellulosic textile material to improve its crease resistance, which method comprises treating the textile with a treatment agent comprising one or more oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid and with an esterification catalyst, and thereafter heating the treated textile to cure the treatment agent onto the fibres of the cellulosic textile.

The invention further includes a treatment solution which comprises an aqueous solution of at least in one oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid, particularly at a concentration of from 0.1 to 30% by weight of the solution, and at least one esterification catalyst, particularly at a concentration of from 0.1 to 30% by weight of the solution.

The invention also includes textile materials treated by the method of the invention or treated using the treatment solution of the invention.

The method is typically is carried out by first impregnating the cellulosic or cellulosic containing textile materials with the aqueous treating solution. Excess liquid can be removed, for example by passing the treated material through wringers and drying to remove the solvent Typically, the treated material is then oven cured at an elevated temperature, for example from about 150 to 2400C for a period of from 5 seconds to 30 minutes, particularly 5 seconds to 5 minutes, to cause cellulose esterification and cross linking.

The term formaldehyde free used in relation to a method herein means that the method does not release formaldehyde vapours during the treatment of textiles or fabrics to improve their wrinkle/crease resistance, during manufacture of garments from finished fabric, during retailing of the garments or apparel goods or use of such goods by consumers.

The term "wrinkle or crease resistance" as used herein means that a treated fabric is less likely to wrinkle/crease or has less wrinkles or crease after being worn or after a laundering operation than it would have, were it not so treated, after a comparable operation.

The term "shape retention/smooth drying" as used herein means that a pre-ironing of textile material fabric or cloth treated according to the invention is less likely to wrinkle or lose its ironed shape after being wom than it would had it not been so treated.

The following Examples illustrate the invention. All parts and percentages are by weight unless otherwise stated.

Example 1 A An oligomer of maleic acid (5.09), prepared by the literature method (free radical polymerisation in xylene as solvent using benzoyl peroxide aas initiator), sodium hypophosphite (5.0 g), ALN-GM (a glyceryl monolaurate 23-ethoxylate surfactant) (1.0 g) and NP-10 (a nonyl phenol 10-ethoxylate surfactant) (100 mg) were dissolved in deionised water (69.0 g). Cotton cloths (10x10 inch; ca 25x25 cm) were dipped in this solution and passed through a wringer to pick up 80% weight of the cloth of the treatment solution. This procedure was repeated twice for each sample and the treated samples stretched on a rack and dried in a forced air draft oven at 900C for 5 minutes.The dry samples were heated to cure them in an air draft oven at 160 C for either 2 (sample 1 a) or 3 (sample I b) minutes as shown in Table 1. After this heat treatment the specimens were washed in hot running water at 45 - 500C for 30 minutes. The samples were then dried in an air forced draft oven for 10 minutes at 900C and conditioned (65% RH; 22 - 240C) for 24 I hours. Wrinkle recovery angles (WRA) were than determined by ICI CAMG-26 method (equivalent to AATCC Test Method 66-1990 "Wrinkle Recovery of Fabrics: Recovery Angle Method). This method is used for determining the wrinkle recovery angles of textiles. The wrinkle resistance of woven textiles is represented in terms of wrinkle recovery angles.The greater is the wrinkle recovery angles more is the wrinkle resistance of the fabric. The results of this study are set out in Table 1 below.

ExamDle 2 Example 1 was repeated except that the treatment solution was made up using 7 g oligomeric maleic acid and 7 g sodium hypophosphite. The samples obtained were 2a (curing at 1600C for 2 minutes) and 2b (curing at 1600C for 3 minutes). The results of testing as described below are included in Table 1. Control samples were made up using untreated cloth (C1) and cloth treated with a conventional formaldehyde based treatment agent based on dimethylol dihydroxyethyleneurea (DMDHEU) (C2).

The DMDHEU used in control C2 was Arkofix NC resin (from Hoechst) which contains 70% DMDHEU resin. The test fabric was treated with 5% of the weight of fabric DMDHEU resin, in the presence of MgCI2 (15% based on the weight of the DMDHEU resin). The resin was applied in a double dip, double nip procedure at a wet pick up of about 80%. After applying the resin solution, the fabric was dried and cured at 1600C for 2 minutes. The fabric was then washed with hot running water at 45 - 500C for 30 minutes, dried in an air forced draft oven for 10 minutes at 900C and then conditioned (65% RH; 22 - 240C for 24 hours). Wrinkle/crease recovery angles were determined on the C1 and C2 samples by the method described above and the results are included in Table 1 below.

The tear strength of treated and untreated fabric was measured using a standard tester manufactured by Testing Machines, Inc. following the TMI method 83-10. The results are expressed as the percentage tear strength of treated cloth as compared with an untreated control.

The results of tear testing are included in Table 1.

A companson in the Whiteness Index of fabric treated with oligomeric/polymeric maleic acid and DMDHEU was made before and after washing at 600C for 12 minutes in a domestic laundry washer after adding detergent (lg.l' in water) on a Milton Roy Colour Match Scan ll. The reflectance in visible range from 400 to 700 nm was measured and the Whiteness Index CIE calculated. The test results on the samples of Examples 1 and 2 and C2 are included in Table 1.

Table 1

Ex Resin1 Cat2 temp time WRA Tear Strength WI No (%) (%) C min warp weft before afler CI 0 0 0 O 207 100 100 74.822 83548 Ia 5 5 160 2 246 75 58 77.738 79.035 1b 5 5 160 3 264 75 58 - 1c 7 7 160 2 259 69 41 - it 7 7 160 3 271 69 41 - - C2 5 - 160 2 282 77 59 70.301 78.286 1 percent concentration of treatment resin in solution.

2 percent concentration of catalyst in treatment solution.

Claims (9)

Claims

1 A method of treating a fibrous cellulosic textile material which method comprises treating the textile with a treatment agent comprising one or more oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid, and thereafter heating the treated textile to cure the treatment agent onto the fibres of the cellulosic textile.

2 A method as claimed in claim 1 wherein the oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid has a molecular weight of from 300 to 100000.

3 A method as claimed in either claim 1 or claim 2 wherein the treatment agent is an aqueous solution of the one or more oligomer(s) and/or polymer(s) of maleic an hydride and/or maleic acid at a concentration of from 0.1 to 30% of the solution.

4 A method as claimed in any one of claims 1 to 3 wherein the treatment agent includes at least one esterification catalyst.

5 A method as claimed in claim 3 wherein the treatment agent solution includes from 0.1 to 30% by weight. of the at least one esterification catalyst.

6 A method as claimed in any one of claims 1 to 5 wherein the treated textile material is subsequently treated at a temperature of from 150 to 2400C to cure the treatment agent onto the textile material.

7 A cellulosic textile material which carries residues of oligomeric and/or polymeric maleic acid and/or an hydride esterified to hydroxylic sites in the cellulose.

8 An aqueous solution containing at least one oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid also containing at least one esterification catalyst.

9 A solution as claimed in claim 8 containing from 0.1 to 30% by weight of the at least one oligomer(s) and/or polymer(s) of maleic anhydride and/or maleic acid and from 0.1 to 30% by weight of the at least one esterification catalyst.