Patent Publication Number: US-2004045144-A1

Title: Method for improving the softness and/or the drape of nonwoven fabrics

Description:
[0001] Priority is claimed to German Patent Application No. DE 102 19 929.9-26, filed May 3, 2002, which is incorporated by reference herein.  
       BACKGROUND  
       [0002] The present invention relates to a method for improving the softness and/or the drape of nonwoven fabrics of non-split and/or at least partially split microfibers and/or microfilaments of synthetic polymers containing at least one polyester component and at least one polyamide component and, possibly, at least one polyurethane component, the nonwoven fabric being subjected to one or more physical treatments according to the method.  
       [0003] Textile materials of synthetic polymers, such as polyamide, polyester, or polyurethane which are manufactured using the classical weave method of warp and weft or by forming loops have been widely used in the most different fields of application, such as in the clothing or automotive industry, because of their many excellent properties.  
       [0004] Nonwoven fabrics, which are manufactured by bonding microfibers and/or microfilaments of these materials, in particular of non-split or at least partially split microfibers and/or microfilaments, are indeed inexpensive to manufacture, but have limited suitability for a number of applications.  
       [0005] A reason for this is, inter alia, that such nonwoven fabrics usually have poor softness as well as unsatisfactory drape. As a result of this, in addition to an unpleasant look, the touch of these nonwoven fabrics is felt to be unpleasant as well, thus reducing, in particular, their comfort of wear. Therefore, such nonwoven fabrics are unusable for a number of applications as, for example, the manufacture of clothing or home textiles, or their possible uses are at least strongly limited.  
       SUMMARY OF THE INVENTION  
       [0006] An object of the present invention is to find a method improving the softness and/or the drape of nonwoven fabrics of non-split and/or at least partially split microfibers and/or microfilaments of synthetic polymers containing at least one polyester component and at least one polyamide component and, possibly, at least one polyurethane component.  
       [0007] The present invention provides a method for improving the softness and/or the drape of nonwoven fabrics of non-split and/or at least partially split microfibers and/or microfilaments of synthetic polymers containing at least one polyester component and at least one polyamide component and, possibly, at least one polyurethane component, the nonwoven fabric being subjected to one or more physical treatments according to the method.  
       [0008] In the context of the present invention, “physical treatment of the nonwoven fabric” is understood to be any treatment of the nonwoven fabric that is carried out while inputting energy. In case the method according to the present invention includes two or more such treatments, these can be carried out simultaneously or in any time order with respect to each other.  
       [0009] In the method according to the present invention, the nonwoven fabric to be treated is preferably used in the form of untreated greige fabric.  
       [0010] Preferably, the nonwoven fabric to be treated is used as a planar structure of any shape in the inventive method. In the method according to the present invention, it is particularly preferred for the nonwoven fabric to be used in the form of panels or webs, even more preferably in the form of webs, preferably analogously to continuous webs of cloth.  
       [0011] The nonwoven fabric used in the inventive method is preferably composed of at least one polyester component and at least one polyamide component, these two plastic components being preferably present in a ratio of 5 to 95 percent by weight of at least one polyester component and 95 to 5 percent by weight of at least one polyamide component, more preferably 15 to 85 percent by weight of at least one polyester component and 85 to 15 percent by weight of at least one polyamide component, even more preferably 30 to 70 percent by weight of at least one polyester component and 70 to 30 percent by weight of at least one polyamide component.  
       [0012] The polyamide component is preferably selected from the group consisting of polyamide 6, polyamide 66 and polyamide 11.  
       [0013] The polyester component is preferably selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polylactic acid, mixtures and copolyesters thereof. Such copolyesters can be manufactured either by partially replacing the acid component and/or by partially replacing the diol component, as described, for example, in Büttner “Basisch modifizierte Polyesterfasern” [Base-Modified Polyester Fibers] in “Die Angewandte Makromolekulare Chemie” [Applied Macromolecular Chemistry and Physics] 40/41, 1974, pages 57-70 (No. 593), or G. G. Kulkarni, Colourage, Aug. 21, 1986, pages 30 through 33. The relevant literature descriptions are hereby incorporated by reference and considered part of the disclosure.  
       [0014] The nonwoven fabric can also preferably contain a polyester based on lactic acid, as described in European Patent EP 1 091 028, as the polyester component. The relevant description is hereby incorporated by reference and considered part of the disclosure.  
       [0015] The titer of the split microfibers and/or microfilaments of the nonwoven fabric used is preferably ≦1 dtex, more preferably 0.1 to 0.25 dtex. The titer of the non-split microfibers and/or microfilaments in the composite is preferably ≧1 dtex, more preferably 2.0 to 3.2 dtex.  
       [0016] The nonwoven fabric used in the method according to the present invention is preferably a staple fiber nonwoven fabric or a spunbonded nonwoven fabric, particularly preferably a spunbonded nonwoven fabric which is preferably processed into webs, preferably analogously to continuous webs of cloth. Such nonwoven fabrics can be manufactured using common methods known to one skilled in the art, as described, for example in Dr. Helmut Jörder “Textilien auf Vliesbasis (Nonwovens)”, avr-Fachbuch, P. Kepler Publishing House, Heusenstamm 1977, page 13 through 20. The manufacture of such spunbonded nonwoven fabrics can preferably be carried out using methods as described European Patent 0 814 188. The relevant descriptions are hereby incorporated by reference and considered part of the disclosure.  
       [0017] Preferred nonwoven fabrics for use in the method according to the present invention are those having a weight per unit area of 15 to 350 g/m 2 , more preferably of 60 to 200 g/m 2 .  
       [0018] The method according to the present invention of physical treatment of the nonwoven fabric can be carried out continuously, semi-continuously or discontinuously, it being usually preferred to run the process continuously.  
       [0019] In a preferred embodiment of the inventive method, the physical treatment of the nonwoven fabric used is carried out according to the present invention by treating the nonwoven fabric mechanically. To this end, the nonwoven fabric is preferably moved in rope form or in web form, preferably in the wet condition.  
       [0020] In a further preferred embodiment of the method according to the present invention, the nonwoven fabric is also subjected to a thermal treatment concurrently with the mechanical treatment. The thermal treatment is preferably carried out using vapor, particularly preferably using supersaturated water vapor. The specific optimum temperature of the vapor as well as the dwell time of the nonwoven fabric in the vapor can vary, for example, as a function of the composition of the fabric, and can be determined by one skilled in the art through preliminary testing.  
       [0021] The temperature of the vapor is preferably not higher than 130° C., more preferably not higher than 120° C. The dwell time of the nonwoven fabric in the vapor is preferably 10 minutes to 90 minutes, more preferably 25 to 75 minutes, and even more preferably 30 to 60 minutes.  
       [0022] The concurrent mechanical and thermal treatment is preferably carried out with vapor in a conventional rope tumbler known to one skilled in the art, such as Type T150S, which is marketed by Thies GmbH &amp; Co. KG (Coesfeld/Westfalen, Germany).  
       [0023] In another preferred embodiment of the present invention, the thermal treatment of the nonwoven fabric can be carried out by washing, preferably in water, using common methods known to one skilled in the art.  
       [0024] The specific optimum temperature during washing as well as the dwell time of the nonwoven fabric in the wash can vary, for example, as a function of the composition of the fabric, and can be determined by one skilled in the art through preliminary testing.  
       [0025] The temperature during washing is preferably 40 to 130° C., more preferably 60 to 95° C. The dwell time of the nonwoven fabric in the wash is preferably 20 to 90 minutes, more preferably 25 to 75 minutes, and even more preferably 30 to 60 minutes.  
       [0026] The mechanical treatment of the nonwoven fabric with concurrent thermal treatment by washing is preferably carried out in a conventional rope washer or rope-dyeing machine known to one skilled in the art, preferably a jet-dyeing machine.  
       [0027] To design the look of the nonwoven fabrics, they are usually also dyed and/or printed using common methods known to one skilled in the art. The physical treatment according to the present invention of this fabric is usually carried out before or after the dyeing and/or printing of the nonwoven fabric.  
       [0028] Suitable dyes for coloring the nonwoven fabric used according to the present invention, include common dyes known to one skilled in the art, in particular, vat and/or sulfur dyes, also in their dissolved form, i.e., in the form of corresponding leuco vat dyes or water-soluble sulfur dyes, inorganic or organic pigments, or disperse dyes.  
       [0029] Preferably usable as a vat dye is a dye selected from the group of anthraquinoid, indigoid, or leuco esters of vat dyes, as described, for example, in “Rath-Lehrbuch der Textilchemie” [Rath&#39;s Textbook of Textile Chemistry], Springer Publishing House, Berlin, Heidelberg, New York, 3 rd  edition, 1972, page 462 through 485. The relevant literature description is hereby incorporated by reference and considered part of the disclosure.  
       [0030] Preferred disperse dyes and corresponding dyeing methods are disclosed, for example, in German patent application, No. DE 101 25 843.7, which is incorporated by reference and considered part of the disclosure.  
       [0031] Preferred inorganic and organic pigments and corresponding dyeing methods are disclosed, for example, in German patent application, File No. 101 29 366.6, which is incorporated herein by reference and considered part of the disclosure.  
       [0032] In case the nonwoven fabric is colored using a rope-dyeing machine, preferably a jet-dyeing machine, the mechanical treatment of the wet nonwoven fabric by movement in rope form can preferably be carried out during dyeing.  
       [0033] The physical treatment and, possibly, the coloring of the nonwoven fabric can be followed by common finishing steps for improving the fabric, which are known to one skilled in the art.  
       [0034] The nonwoven fabrics of non-split and/or at least partially split microfibers and/or microfilaments of synthetic polymers containing at least one polyester component and at least one polyamide component and, possibly, at least one polyurethane component that are treated according to the inventive method feature improved softness and/or improved drape properties. Thus, due to the very nice look and the soft nature of this material, which is perceived as pleasant, they are suitable, in particular, for manufacturing high-quality products as, for example, clothing, shoe components, home textiles, cover fabrics, flags, lining fabrics, preferably those for baggage pieces, products for medical or hygienic applications, as well as for manufacturing the trim of means of transportation, preferably the interior trim of means of transportation. In the context of the present invention, “means of transportation” are understood to include vehicles, in particular, motor vehicles, rail vehicles, watercraft and aircraft.  
       [0035] Therefore, a further subject matter of the present invention is the use of at least one nonwoven fabric treated according to the present invention for manufacturing clothing, shoe components, home textiles, cover fabrics, flags, lining fabrics, preferably lining fabrics for baggage pieces such as suitcases or bags, products for medical applications, hygienic products, as well as for manufacturing the trim of means of transportation, preferably the interior trim of means of transportation.  
       [0036] Surprisingly, it was discovered that such nonwoven fabrics, after treatment according to the inventive method, usually have improved stretch properties, in particular, in the transverse direction, as well as improved strengths, in particular, maximum tensile strengths and tear propagation strengths.  
       [0037] The softness of the nonwoven fabrics is assessed by test persons touching the nonwoven fabric material, each of the test persons giving a rating from 1 to 6. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0038] The present invention is explained below with reference to the drawing, in which:  
     [0039]FIG. 1 shows a method for improving a quality of a fabric. 
    
    
     DETAILED DESCRIPTION  
     [0040] Referring to FIG. 1, according to a method for improving a quality of a fabric, a a nonwoven fabric containing at least one of microfibers and microfilaments of synthetic polymers and including a polyester component and a polyamide component is provided (see block  11 ). The nonwoven fabric is then subjected to at least one physical treatment so as to improve at least one of a softness and a drape of the nonwoven fabric (see block  12 ).  
     [0041] The present invention is explained further below with reference to to examples. These explanations are by way of example only and do not limit the general idea of the present invention.  
     EXAMPLE 1)  
     [0042] Washing in rope form on a jet-dyeing machine  
     [0043] A spunbonded nonwoven fabric in web form which is bonded using the water-jet technology, has a weight per unit area of 100 g/m 2 , and which is composed of partially split microfilaments of 70 percent by weight of polyethylene terephthalate and 30 percent by weight of polyamide 6 having a titer of 0.10-0.15 dtex was treated in the form of untreated greige fabric with 2 ml/l of the running aid Sevosoftal® UFB (Textilcolor, Sevelen, Switzerland) at a liquor ratio of 1:30, using a method for fabric in rope form.  
     [0044] Washing was started at 20° C., followed by heating at a rate of 2° C. per minute to 115 ° C., and treatment for 30 minutes at this temperature. After that, cooling was carried out at a rate of −1.5° C. per minute to 70° C., followed by rinsing with cold water. The circulation speed of the nonwoven fabric was 100 m/minute during the entire process.  
     [0045] Finally, drying was carried out for 40 seconds at a temperature of 130° C. with little stress on a screen-belt dryer (Type Santashrink, Santex AG, Tobel, Switzerland).  
     COMPARATIVE EXAMPLE 1)  
     [0046] To rule out that the improvement of the properties of the nonwoven fabric is attributable to the influence of the screen-belt dryer, a part of the untreated greige fabric used according to example 1a) was wetted with water by simply using a conventional padding mangle at a liquor pick-up of 90 percent by weight with respect to the weight per unit area of the nonwoven fabric used, and then this nonwoven fabric is dried analogously to the nonwoven fabric treated in rope form according to example 1a.  
     EXAMPLE 2)  
     [0047] Treatment using a discontinuously operating rope tumbler  
     [0048] A spunbonded nonwoven fabric in web form which is bonded using the water-jet technology, has a weight per unit area of 100 g/m 2 , and which is composed of partially split microfilaments of 70 percent by weight of polyethylene terephthalate and 30 percent by weight of polyamide 6 having a titer of 0.10-0.15 dtex was treated in the form of untreated greige fabric for 40 minutes at a temperature of 130° C. in a water vapor atmosphere in a rope tumbler (Type T150S, Thies GmbH &amp; Co. KG) at a circulation speed of 80 meters/minute. Then, the so-treated nonwoven fabric was cooled down to 80° C. within 20 minutes without further supply of vapor, and removed from the machine.  
     EXAMPLE 3)  
     [0049] Treatment with concurrent jet dyeing  
     [0050] A spunbonded nonwoven fabric in web form which is bonded using the water-jet technology, has a weight per unit area of 100 g/m 2 , and which is composed of partially split microfilaments of 70 percent by weight of polyethylene terephthalate and 30 percent by weight of polyamide 6 having a titer of 0.10-0.15 dtex was dyed according to the exhaust process in a dyeing machine (Type Soft TRD, Thies GmbH &amp; Co. KG Coesfeld/Westfalen, Germany).  
     [0051] To this end, Foron® Blue RD-GLF disperse dye (Clariant, Frankfurt, Germany) in an amount of 0.7 percent by weight with respect to the weight per unit area of the nonwoven fabric used was applied at pH 4.5 and a liquor ratio of 1:30 in the presence of 1.5 ml/l of the levelling agent Eganal® PS (Clariant, Frankfurt, Germany) and 2 ml/l of the running aid Sevosoftal® UFB (Textilcolor, Sevelen, Switzerland), 2 ml/l of acetic acid, 60 percent by weight, and 2 g/I of sodium acetate. The dyeing of the nonwoven fabric was started at 20° C., followed by heating at a rate of 2° C./minute to 130° C., and dyeing for 30 minutes at this temperature. After that, cooling was carried out at a rate of 1.5° C./minute to 70° C., followed by rinsing with cold water and, at a liquor ratio of 1:30, reduction cleaning was carried out with 6 ml/l of sodium hydroxide solution, 32 percent by weight, and 2 g/I of concentrated hydrosulfite (BASF AG, Ludwigshafen, Germany) for 20 minutes at 85° C. After that, the nonwoven fabric treated and dyed in this manner was rinsed with cold water and neutralized with 1 ml/l of acetic acid, 60 percent by weight. The circulation speed of the nonwoven fabric was 100 meters/minute during the entire dyeing process.  
     [0052] Finally, drying was carried out on a screen-belt dryer (Type Santashrink, Santex AG, Tobel, Switzerland) for 40 seconds at a temperature of 130° C. with little stress.  
     [0053] Assessment of the treated nonwoven fabrics:  
     [0054] To determine the softness, fabric samples were assessed in terms of the perceived feel before and after the respective treatment specified in the examples 1-3 and comparative example 1 by 20 test persons (10 women, 5 of whom aged between 20 and 35 years and 5 aged between 35 and 50 years; 10 men, 5 of whom aged between 20 and 35 years and 5 aged between 35 and 50 years).  
     [0055] Accordingly, the rating relates to the assessment of the treated fabric sample compared to the untreated fabric sample. In this context, grade 1 was given as the best rating (very pleasant and very soft) and grade 6 as the worst rating (no improvement).  
     [0056] The corresponding ratings by the test persons are represented in Table 1 below.  
                               TABLE 1                               Comparative               Test Person   Example 1   Example 1   Example 2   Example 3                                                    1   1   5   2   2       2   2   5   2   2       3   2   6   1   1       4   2   5   1   2       5   1   6   2   2       6   1   6   2   1       7   2   5   2   3       8   1   6   2   1       9   2   6   3   3       10   3   6   2   2       11   2   6   2   2       12   2   6   3   3       13   2   6   3   2       14   1   6   2   2       15   3   6   2   2       16   3   6   3   3       17   3   6   2   2       18   3   6   3   2       19   2   6   2   3       20   3   6   2   3                  
 
     [0057] The nonwoven fabrics treated according to examples 1-3 using the inventive method each exhibit markedly improved softness over the untreated nonwoven fabric.  
     [0058] Comparative Example 1 verifies that drying by the screen-belt dryer has little influence on the softness of the nonwoven fabrics.