Abstract:
A pigment printing dyestuff composition for textile finishing comprises a cyclodextrin or cyclodextrin derivative in turn capable of including a scent as a guest molecule.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    A pigment printing dyestuff for textile finishing comprises a cyclodextrin (CD) or cyclodextrin derivative in turn capable of including a scent as a guest molecule.  
           [0003]    2. The Prior Art  
           [0004]    Cyclodextrins (CD) are cyclic oligosaccharides constructed of 6, 7 or 8 α(1-4)-linked anhydroglucose units. The α-, β- or γ-cyclodextrins, which are prepared by enzymatic conversion of starch, differ in the diameter of their hydrophobic cavity and are generally suitable for the inclusion of numerous lipophilic substances.  
           [0005]    Cyclodextrin derivatives are prepared by chemical modification of the —OH groups of cyclodextrin. Examples of customary modifying chemistries are hydroxypropylation using propylene oxide and methylation using methyl halides. The cyclodextrin derivatives thus obtained are substantially more soluble in water than native cyclodextrins and are capable of solubilizing inherently water-insoluble, hydrophobic substances in an aqueous medium by inclusion and formation of water-soluble complexes.  
           [0006]    Printing is local color dyeing in zones corresponding to a pattern. Conformation to these zones dictated by the engraved pattern is ensured by the thickening of the color. The type and size of the artistic design determine the printing process and the dyestuff paste application method. Each printing technique is carried out using a specific printing process, which is usually based on a uniform sequence of operations (printing, drying, steaming, washing).  
           [0007]    The pigment printing process is known in textile finishing as an inexpensive technology which is easy to carry out. In it, patterns are applied to fabrics using suitable screen printing stencils, for example. Screen printing stencils are partially pervious, so that a printing dyestuff, generally a printing paste, can be applied by means of suitable squeegees on a printing machine. Pigment printing utilizes color dye pigments which are devoid of any chemical bonding to the substrate to be printed. In order that they may nonetheless be fixed on the substrate, a binder is employed to combine with the pigments to form a kind of colored film. Such binders are for example thermally crosslinkable acrylates, polyurethanes and butadiene-styrene copolymers. Other binders are known as well. To ensure crisp contours in opposition to the capillary forces of the substrate, the system is thickened with thickeners to values which are preferably between 5 000 and 20 000 cSt. It is customary to reduce abrasion by adding a silicone emulsion which additionally is capable of positively influencing the hand as well.  
           [0008]    After application to the textile, the print is dried and fixed. This is preferably accomplished by treating the print at around 150-190° C. for several minutes, in the course of which the water in the printing paste evaporates and the binder is rendered insoluble by crosslinking. As a result, the color dye pigment is bound to the substrate. The print is not washed and so the pigment printing process creates virtually no wastewater. This process is therefore very popular for economic and ecological reasons; more than 50% of the world&#39;s printed yardage is produced in this way.  
           [0009]    A printed fabric possesses visual appeal by virtue of color and design. But customers are increasingly desirous of additional, olfactory stimuli; that is, the fabric shall also have an appealing odor.  
           [0010]    Odorants, however, are volatile, by their very nature. Perfumed fabric would thus very rapidly lose its odor. To remedy this disadvantage, it is known to include odorants in microcapsules and to incorporate these doped microcapsules in printing pastes. The microcapsules are then fixed by the binder as well. If, then, a fabric which has been printed in this way is rubbed, the microcapsules will burst and immediately release the scent. Due to the high costs of such perfumed microcapsules, this method is costly and limited to a single emission of odorant. It has therefore only found very restricted use.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the present invention to provide a pigment printing dyestuff for textile finishing that, after application to the textile, can be activated in the course of the wearing of the textile; possesses a long-lasting scent effect; and can be reactivated by reloading with odorant.  
           [0012]    This object is achieved by a pigment printing dyestuff composition which includes a cyclodextrin or cyclodextrin derivative in turn capable of including a scent as a guest molecule.  
           [0013]    The printing dyestuff composition according to the invention preferably comprises a cyclodextrin or cyclodextrin derivative complexed with a scent.  
           [0014]    It is possible to use α-, β- or γ-cyclodextrin or derivatives thereof or mixtures thereof. Hydroxypropyl and methyl derivatives of α-, βor γ-cyclodextrin will be found to be particularly advantageous,  
           [0015]    The printing dyestuff composition according to the invention preferably includes from 1 to 15% by weight of cyclodextrin or cyclodextrin derivative, based upon the total weight of the composition.  
           [0016]    The printing dyestuff composition preferably includes from 0.1 to 1.5% by weight of a scent, based upon the total weight of the composition.  
           [0017]    More particularly, the present invention provides a printing paste dyestuff composition, comprising  
           [0018]    70 g of methyl-β-cyclodextrin; dissolved in 400 g of deionized water; 7 g of perfume oil (a scent); 100 g of silicone dispersion; 100 g of polyurethane binder, 50 g of silicone oil emulsion; 1 g of dye; 192 g of deionized water; and 80 g of thickener.  
           [0019]    Also, the present invention provides a printing paste dyestuff composition comprising  
           [0020]    70 g of hydroxypropyl-β-cyclodextrin; dissolved in 400 g of deionized water; 7 g of perfume oil (a scent); 100 g of silicone dispersion; 100 g of polyurethane binder; 50 g of silicone oil emulsion; 10 g/liter of dye; 183 g of deionized water; and 80 g of thickener.  
           [0021]    In addition, the present invention provides a printing paste dyestuff composition comprising  
           [0022]    a cyclodextrin derivative in an amount ranging from 1% to 15% by weight, based upon the total weight of the dyestuff composition; a scent in an amount ranging from 0.1% to 1.5% by weight, based upon the total weight of the dyestuff composition;  
           [0023]    water in an amount ranging from 40% to 60% by weight, based upon the total weight of the dyestuff composition; and from 23.5% to 58.9% by weight of a dye and an ingredient selected from the group consisting of a silicone dispersion, a polyurethane binder, a silicone oil, a thickener, and mixtures thereof.  
           [0024]    The term “scent” as used herein also comprehends essences and aromas, The scent is preferably selected from the group consisting of fruity notes based on citral (lemon scent), allyl caproate, rose oil, substances having rose scent, citral, substances having lemon scent, apple aroma, vanillin, cinnamaldehyde (pineapple), prenyl acetate (banana), heliotropin (cherry), agruma oils; herbal notes based on lavender oil, rosemary oil, thyme oil, sage oil, peppermint oil, eucalyptus oil, tea tree oil, camomile oil, spicy notes based on cinnamaldehydes (cinnamon), eugenol (clove flower); woody notes based on sandalwood oil, cedar oil, cyprus oil and rosewood oil; flowery scents based on ionone (violet), terpineol (lilac), phenylethyl alcohol/citronellol (rose), hydroxycitronellol (lily of the valley); alpha-hexylcinnamaldehyde/benzyl alcohol (jasmine), ylang-ylang oil (ylang-ylang); animalistic notes based on polycyclic and also macrocyclic compounds (musk); sweet, balsamic notes based on vanillin (vanilla), anethole (aniseed), benzaldehyde (almond), courmarin (moss, hay).  
           [0025]    Useful printing dyestuffs include all known, customary pigment printing dyes. The pigment printing dyestuff is preferably a paste. More preferably, it is an aqueous pigment printing dyestuff or paste, of which aqueous pigment printing pastes are particularly preferred.  
           [0026]    Cyclodextrins and cyclodextrin derivatives are soluble in water and therefore are readily incorporated into aqueous printing dyestuffs. Dissolved in water, they have the useful property of encapsulating water-insoluble odorants, so that these can be taken up in the aqueous system simply by stirring into an aqueous cyclodextrin solution.  
           [0027]    The pigment printing dyestuff composition according to the invention is easily preparable by incorporating a cyclodextrin, a cyclodextrin derivative, a cyclodextrin or cyclodextrin derivative and subsequently a scent, a cyclodextrin-scent complex or a cyclodextrin derivative-scent complex in the printing dyestuff by stirring or kneading.  
           [0028]    The incorporating is preferably effected at 20 to 60° C. under atmospheric pressure. The incorporating time is preferably between 1 and 30 minutes.  
           [0029]    The cyclodextrin-scent complex can be produced not only during the making of the printing dyestuff composition by addition of a scent to an aqueous cyclodextrin-containing printing dyestuff but also separately using an aqueous cyclodextrin solution and then be incorporated in a customary printing dyestuff.  
           [0030]    A cyclodextrin-scent complex is preparable in a conventional manner, for example from solution or by the paste method. An advantageous way is to prepare it from an aqueous solution or suspension of cyclodextrin or cyclodextrin derivative.  
           [0031]    The CD concentration of the aqueous solution or suspension is between 1-60% by weight based upon the total weight of the aqueous solution or suspension. Preference is given to a CD concentration of 10-20% based upon the total weight of the aqueous solution or suspension. The weight ratio of scent to CD is between 1:100 and 1:1, preferably between 1:20 and 1:5. The batches are intensively stirred or kneaded, depending on the consistency.  
           [0032]    The reaction temperature is customarily at 20-80° C. Preference is given to a reaction temperature of 20-60° C. and more preference to a reaction temperature of 20-40° C. The complexing time depends on the reaction temperature and is between a few minutes and several hours. Preference is given to a reaction time of 1 to 30 minutes.  
           [0033]    The complexing is generally effected under atmospheric pressure. The complexing preferably takes place in a contained system in order that loss of scent during the complexing may be prevented.  
           [0034]    Mixing this odorant-containing cyclodextrin solution with the customary ingredients of a pigment printing dyestuff composition gives a printing dyestuff having an individual scent note.  
           [0035]    The printing dyestuff according to the intention is applied to the textile in a customary manner known for the corresponding non-cyclodextrin-containing printing dyestuff. The odorants present in the printing dyestuff are then applied to the textile in the form of their cyclodextrin complexes in the course of the printing and drying operation and are fixed by the binder present in the printing ink The invention thus also provides for the use of a printing ink according to the invention for printing textiles.  
           [0036]    The printing inks according to the invention make it possible to produce attractive, fragrant, printed textiles in a simple and inexpensive manner.  
           [0037]    The invention thus also provides textiles printed with a pigment printing ink according to the invention.  
           [0038]    Odorants may be chosen to harmonize with the dye and the design. For instance, rose oil can be combined with a red pigment to print a floral motif, or lemon oil can be combined with a yellow pigment and apple aroma with a green pigment to print fruit motifs. The unity of visual and olfactory sensations creates an hitherto unattainable whole.  
           [0039]    The printing dyestuff according to the invention, after it has been applied to the textile, offers two further advantages over the prior art:  
           [0040]    Firstly, the odor components are released under the influence or heat and moisture, i.e., conditions which are the natural result of the wearing of garments. Robust mechanical action as in the case of microcapsules is not needed.  
           [0041]    Secondly, the bound cyclodextrins are rechargeable with the scent, whereas microcapsules have to be irreversibly destroyed.  
           [0042]    A textile printed with a pigment printing dyestuff Composition according to the invention can be provided with new scent simply by spraying with an aqueous scent solution or suspension, The scent is initially taken up by the cyclodextrin. As the printed garment is worn, the scent is then gradually released under the action of heat and moisture.  
           [0043]    The invention thus further provides a process of spraying a textile according to the invention with an aqueous scent solution.  
         DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
         [0044]    The examples hereinbelow illustrate the invention. 
       
    
    
     EXAMPLE 1  
       [0045]    A printing paste was prepared at room temperature by the following method:  
         [0046]    70 g of methyl-β-cyclodextrin (CAVASOL® W7 M) were dissolved in 400 g of deionized water. 7 g of rose type 131650 perfume oil from Kurt Kitzing GmbH, Wallerstein were added with stirring. After just 1 minute, the water-insoluble oil formed a clear solution in the cyclodextrin solution.  
         [0047]    This solution was admixed with  
         [0048]    100 g of Finish CT 27 E (Wacker silicone dispersion),  
         [0049]    100 g of Emuldur DS 2360 (BASF polyurethane binder),  
         [0050]    50 g of Finish C 800 (Wacker silicone oil emulsion) and  
         [0051]    1 g of Helizarin Brilliant Red BBT (BASF).  
         [0052]    Then  
         [0053]    192 g of deionized water and  
         [0054]    80 g of Appretan thickener 3308 (Clariant) were added to prepare 1 kg of printing paste.  
         [0055]    The printing paste was subsequently homogenized by stirring with a bladed stirrer at 800 rpm for 10 minutes.  
         [0056]    This printing paste according to the invention was applied through a screen printing stencil bearing a rose motif onto bleached 100% cotton knit and dried. The pink flowers exude an intense rose scent on contact with the naked forearm, for example, after adjustment to body heat and body moisture.  
       EXAMPLE 2  
       [0057]    Example 1 was repeated with the following differences: the cyclodextrin used was hydroxypropyl-β-cyclodextrin (CAVASOL® W7 HP), the perfume oil was Citral 54450 from Drom and the dye used was Helizarin Yellow GTN (BASF), at 10 g per liter. This reduces the amount of water needed from 192 g to 183 g.  
         [0058]    This paste according to the invention was printed onto a customary 65/35 polyester/cotton fabric in a lemon motif. The fruit design exuded a fresh fruity odor under conditions as mentioned in Example 1.  
         [0059]    Accordingly, while only several embodiments of the present invention have been shown and described, it is obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.