Patent Publication Number: US-2002007517-A1

Title: Cyclodextrin-based soft-hand compositions for textiles

Description:
[0001] This invention relates to aqueous dispersions that include a cyclodextrin, a carboxylic acid and a cationic surfactant. It further relates to the use of such dispersions for treating fiber materials, especially textile fabrics.  
       [0002] It is known to treat textiles with products that include sugar derivatives in order that a soft hand may be imparted to the textiles. This is known for example from EP 792 337 B1. Similarly, the treatment of textile materials with cyclodextrins is known and described in DE-A 4 035 378. The treatment of textile fabrics with cyclodextrins has the advantage that, owing to the well-known properties of cyclodextrins, the treated textiles will absorb perspiration and so reduce unpleasant odorization. The cited DE reference also says that cyclodextrins may be used together with cellulose crosslinkers to obtain permanent fixation of the finish to the textiles.  
       [0003] U.S. Pat. No. 5,234,611 describes fabric softeners that include polymer-encapsulated cyclodextrins. They are used for home laundry operations.  
       [0004] Despite the well-known advantages of cyclodextrins, prior art formulations with cyclodextrins have the disadvantage that the hand of textiles treated therewith does not possess optimum softness. This applies in particular when prior art formulations are applied to non-made-up textile fabrics in the course of a textile finishing operation.  
       [0005] It is an object of the present invention to provide aqueous dispersions for the treatment of fiber materials, especially non-made-up textile fabrics, which retain the advantages of cyclodextrin formulations while producing a very soft hand.  
       [0006] This object is achieved by an aqueous dispersion including at least the following components:  
       [0007] A) an unsubstituted cyclodextrin or a mixture of such cyclodextrins  
       [0008] B) an aliphatic carboxylic acid of 8 to 24 carbon atoms or a mixture of such carboxylic acids  
       [0009] C) a cationic surfactant or a mixture of such surfactants,  
       [0010] said components A to C accounting for 10 to 40% by weight of said dispersion and said dispersion including said components A, B and C in the following amount ratios relative to each other:  
       [0011] A): 10 to 20 parts by weight  
       [0012] B): 25 to 80 parts by weight  
       [0013] C): 25 to 150 parts by weight.  
       [0014] Dispersions according to the invention can be applied to the fiber materials by known methods, for example by padding. For this, the padding liquor is adjusted to a concentration customary in textile finishing and to the desired pH. The aqueous dispersions of the invention, or the padding liquors, may include further products as well as the abovementioned components A, B and C. Such further products can be customary textile finishing ingredients such as flame retardants, polyolefins, and also silicones and fluoropolymers for oil and/or water repellency. More particularly, aqueous dispersions according to the invention may additionally include known cellulose crosslinkers such as dimethyloldihydroxyethyleneurea for example. This, following an appropriate, known thermal treatment of the fiber materials, will improve the durability of the effects obtainable with inventive dispersions on cellulose textiles.  
       [0015] When dispersions according to the invention are used for textile treatment the known advantages of cyclodextrins are retained. These include, first, the ability to absorb perspiration or volatile gaseous products and so reduce odor nuisance. Secondly, cyclodextrins are known to be useful for including active ingredients such as scents in their voids and to rerelease them at a controlled rate in small doses. This makes it possible to impart a pleasant odor to textiles. For this purpose, the scent is combined with cyclodextrin according to known methods.  
       [0016] In addition to the advantages due to cyclodextrin, dispersions according to the invention provide a very pleasant soft hand and a controllable level of hydrophilicity. Aqueous dispersions according to the invention may also be used with advantage for textile treatment in exhaust processes. The hydrophilicity of the textiles can be controlled via the relative amounts of the components A, B and C or via the addition of nonionic dispersants, as described hereinbelow.  
       [0017] It was found that, surprisingly, dispersions according to the invention provide a distinct, synergistic effect with regard to the soft hand of textiles treated therewith. The hand obtainable with compositions according to the invention is softer than the hand obtained with each one of the components A, B and C taken alone. Apart from that, it is difficult in many cases to prepare stable aqueous dispersions that contain only a component A and a component C, but not a component B.  
       [0018] It is also surprising that the pronounced hydrophilic properties imparted to the fiber materials by cyclodextrins in known manner deteriorate only to an acceptable degree, if at all, on addition of long-chain fatty acids. Dispersions according to the invention thus provide markedly hydrophilic properties and a very soft hand on fiber materials.  
       [0019] Dispersions according to the invention include at least the three hereinbelow more particularly described components A, B and C. As mentioned, they may additionally include further ingredients.  
       [0020] Component A is an unsubstituted cyclodextrin or a mixture of such cyclodextrins. Cyclodextrins are cyclic oligosaccharides made up of 6, 7 or  8  α-1,4-glycosidically linked D-glucopyranose units, in line with the definition in H. R. Christen et al.,  “Organische Chemie, Von den Grundlagen zur Forschung” , volume II, page 549, 1st edition 1990, Otto-Salle-Verlag, Frankfurt/M. The compounds with 6, 7 and 8 units are termed respectively α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin. Cyclodextrins are bacterial degradation products of starch. Particularly preferred dispersions according to the invention include at least β-cyclodextrin. They may additionally include α- and/or γ-cyclodextrin. Cyclodextrins are commercial products, available for example from Wacker Chemie, Germany.  
       [0021] Component B is an aliphatic carboxylic acid of 8 to 24 carbon atoms or a mixture of such carboxylic acids. Linear or branched, saturated or unsaturated acids such as oleic acid can be used. Component B may further include monobasic or polybasic carboxylic acids. Component B preferably comprises saturated unbranched monobasic carboxylic acids (monocarboxylic acids) such as stearic acid or behenic acid. For cost reasons, component B normally comprises a mixture of technical grade carboxylic acids having a customary chain length distribution.  
       [0022] Component C is a cationic surfactant or a mixture of cationic surfactants. Useful cationic surfactants include the surface-active compounds known from the technical literature. Ammonium salts of inorganic or short-chain organic acids are very suitable for dispersions according to the invention. The cation of these salts may contain a quaternized nitrogen atom, but it is also possible for up to 3 hydrogen atoms to be attached to the nitrogen atom. In preferred dispersions according to the invention, component C includes a surfactant of the general formula (I)  
                 
 
       [0023] where  
       [0024] m is 0 or 1  
       [0025] n is from 1 to 8  
       [0026] p is 1 or2  
       [0027] q is 0, 1 or 2  
       [0028] r is 0, 1 or 2  
       [0029] q+r is 2 or 3 and  
       [0030] R 1  is an alkyl radical of 8 to 20 carbon atoms,  
       [0031] R 2  and R 3  are independently hydrogen, an alkyl radical of 1 to 6 carbon atoms or a radical of the formula  
                 
 
       [0032] where t is from 1 to 30,  
       [0033] and X ⊖  is a monovalent anion of an inorganic or organic acid.  
       [0034] Very suitable surfactants have, for example, the formula (I) where m=0, p=1, q=2, R 2 =H,  
                 
 
       [0035] and where X ⊖  is the anion of monomethyl sulfate or the anion of a hydroxycarboxylic acid of 2 to 4 carbon atoms. Other surfactants useful as component C have the formula (I) where m=1, p=2, q=1, r=1 and R 2  is hydrogen and  
                 
 
       [0036] X ⊖  being an anion of the abovementioned kind. Useful anions X ⊖  further include for example the anion of acetic acid, propionic acid, glycolic acid or lactic acid. R 1  in the formula (I) is a linear or branched alkyl radical of 8 to 20 carbon atoms. Alkyl R 2  or R 3  contains 1 to 6 carbon atoms and may be linear or branched.  
       [0037] Dispersions according to the invention include the components A, B and C in the following amount ratios relative to each other:  
       [0038] A): 10 to 20 parts by weight  
       [0039] B): 25 to 80 parts by weight  
       [0040] C): 25 to 150 parts by weight.  
       [0041] When one or more of the components A, B or C are mixtures, these amount statements are each based on the sum total of all ingredients of these mixtures. These amount ratios can be varied to influence the hand and hydrophilicity of finished textiles in a specific manner.  
       [0042] It can be of advantage for certain applications for dispersions according to the invention to additionally include a nonionic surfactant or a mixture of such surfactants. Particularly useful nonionic surfactants are ethoxylated carboxylic acids and ethoxylated alcohols. Silicones having polyoxyethylene groups or having amino groups in side chains can also be used, either alone or combined with the abovementioned nonionic surfactants. The addition of these nonionic dispersants can additionally increase the hydrophilic properties of the textiles. When dispersions according to the invention are to be used to treat textile fabrics consisting wholly or essentially of cellulose fibers, it is frequently of advantage to use a cellulose crosslinker as well. N-Methylol compounds known from the literature are useful for this purpose, but also so-called “formaldehyde-free” or “low-formaldehyde” crosslinkers. Suitable cellulose crosslinkers are obtainable from Ciba Spezialitätenchemie Pfersee GmbH, for example products of the KNITTEX® range. Application of such dispersions to fiber materials and drying is followed by a customary thermal treatment, for example at 160° C., to effect the crosslinking with the cellulose material. Following this treatment, the effects obtainable with dispersions according to the invention exhibit enhanced durability.  
       [0043] Aqueous dispersions according to the invention include 10 to 40% by weight of the sum total of components A, B and C. The remainder is either just water or water and other ingredients, for example of the abovementioned kind. Such aqueous dispersions can be prepared according to commonly known methods, for example by initially charging water, adding the individual components in any order and homogenizing the mixture at 40° to 100° C. by mechanical agitation. Alternatively, a mixture of the components A, B and C can be prepared without the use of water and stirred into water.  
       [0044] Aqueous dispersions according to the invention are particularly useful for treating non-made-up textile fabrics in the form of wovens or knits. This treatment accordingly preferably takes place on the premises of the textile finisher and not on the garment in the home.  
       [0045] The fiber materials which are preferably present as non-made-up wovens or knits can be further processed into articles of clothing. They may be comprised of natural fibers such as wool or cotton, of regenerated fibers such as viscose or synthetic fibers such as nylon or polyester or of blends of the fiber varieties mentioned.  
       [0046] The invention will now be illustrated by examples. 
     
    
    
     EXAMPLE 1 (inventive)  
     [0047] An aqueous dispersion 1 was prepared by mixing together the hereinbelow specified components and homogenizing at about 80° C.:  
     [0048] Component a)=β-cyclodextrin (=component A of claim  1 )  
     [0049] Component b)=technical grade saturated monocarboxylic acid having on average 20 carbon atoms (=component B of claim  1 )  
     [0050] Component c)=quaternary ammonium salt of ethoxylated stearylamine and glycolic acid (=component C of claim  1 )  
     [0051] Component d)=bis(acyloxyethyl)methylhydroxyethylammonium methylsulfate (=component C of claim  1 )  
     [0052] Component e)=ethoxylated C16-C18-alcohol  
     [0053] Component f)=modified polydimethylsiloxane having polyoxyethylene groups in side chains  
     [0054] Component g)=water  
     EXAMPLE 2 (comparative)  
     [0055] A dispersion 2 was prepared by the same method as dispersion 1. Dispersion 2 included the same components in the same amounts as dispersion 1 except that dispersion 2 did not include component b (=component B of claim  1 ).  
     [0056] Dispersions 1 and 2 had the compositions reported in the table which follows.  
                                           TABLE                           Parts by   Parts by   Parts by   Parts by   Parts by   Parts by   Parts by           weight of   weight of   weight of   weight of   weight of   weight of   weight of       Dispersion   component a   component b   component c   component d   component e   component f   component g                                                                1   2.2   6.2   5.3   3.2   0.7   0.4   82.0       2   2.2   0   5.3   3.2   0.7   0.4   82.0                  
 
     [0057] Dispersions 1 and 2, which were both stable, were used to treat (pad) various wovens and knits composed of cotton, cotton/polyester, polyester and nylon, which were subsequently dried. The hand was then assessed, and the hydrophilicity of the textile fabrics was determined, by measuring the time for a drop of water to penetrate into the textile fabric.  
     [0058] It was found that in all cases there was hardly any difference between the two dispersions with regard to the hydrophilicity of the textile fabrics. However, the hand obtained with dispersion 1 was distinctly softer and more pleasant on all textile fabrics than from the use of dispersion 2.