ABRASION RESISTANT, HIGH BULK FIBER

Abstract: High bulk copolymer filaments of polydiorganosiloxane modified base polymers provide high coverage fibers demonstrating exceptional abrasion resistance and are useful in a number of applications, especially lower weight automotive carpets.

Description: ABRASION RESISTANT, HIGH BULK FIBER Field of the Invention The present invention relates to improved fibrous materials useful in the manufacture of carpet, upholstery and fabrics in applications where both abrasion resistance and weight savings due to material use minimization are of significance. Background of the Invention There is a constant search in the fiber industry for higher bulk materials that can make products lighter, i.e., provide an equivalent amount of "cover" and "bulk" with a smaller amount of material. There is a concurrent objective to make such materials more abrasion resistant or, alternatively, to provide equivalent abrasion resistance with less material. This is particularly true in the carpet, upholstery, luggage and recreational gear arenas where the development of fibers that exhibit exceptional abrasion resistance, high cover and bulk, to thereby reduce weight or cost, is a continuing objective. One method for improving the abrasion resistance of fibers in carpet or fabric applications is to surface modify the fibers or fiber-containing article with a topical finish. Unfortunately, reducing the amount of these treated fibers (to lower weight) results in a significant loss of cover and bulk. In addition, the surface applied finishes give only temporary abrasion performance due to material loss from wet processing, wear and/or cleaning of the fibers or fiber-containing article. Another method for improving the abrasion resistance and cover of, for example, a carpet is to use a greater amount of filament or fiber per unit of area. This, of course, defeats the objective of reducing the overall carpet weight. The current art restricts the amount of material that can be used for a given abrasion performance level. To address the bulk or cover issue, lobed and/or void-containing filaments have been developed. See, e.g., U.S. Patents 4,770,938; 5,108,838; 5,190,821 ; 5,208,106; 5,208,107; 5,230,957; 5,279,897; 5,322,736; 5,362,563; 5,380,592; 5,523,155, all of which are incorporated by reference. Such filaments do not, in and of themselves, demonstrate any increased abrasion resistance; however, they do permit the use of less material to achieve an equivalent cover. Other pertinent art has been used to increase the softness, water repellency and/or processability of polyamide or polyester fibers. See, for example, U.S. Patent 3,511 ,699, that describes the topical application, with or without a catalyst, of an epoxy functional polydimethylsiloxane to fiber to increase its softness and water repellency, and European Patent No. 0 703 938 B1 (International Publication WO 94/28054), that describes the incorporation of a polydiorganosiloxane into a base polymer to improve processability. There is, however, no mention of any increase in the abrasion resistance of the products of these references. Summary of the Invention It is therefore an object of the present invention to provide a polymeric filament or fiber that simultaneously demonstrates greatly improved abrasion resistance and cover, and consequently permits the use of less material to achieve an equivalent level of both cover and abrasion resistance. Stated in another fashion, it is the objective of the present invention to provide a polymeric fiber and articles made therefrom that have good abrasion resistance and aesthetics (cover and bulk) at a significantly lower fiber weight. It has now been surprisingly discovered that when the polydiorganosiloxane-modified polyamide and polyester copolymers described in European Patent 0 703 938 are converted into high bulk filament, significant increases in abrasion resistance are achieved for products made therefrom as compared to products produced with other prior art filaments, and up to about 30 percent less filamentary material is required to produce an article having abrasion resistance equivalent to one made from unmodified (polymeric) filament. Thus, a lightweight, abrasion resistant article having excellent cover can be readily produced. The copolymer of EP 0 703 938 has a structure represented by the following formula A: R 2 | 1 Ri - - Ri 1 I 1 1 R 2 R 2 1 1 1 I z Z (A) wherein each of Ri is the same or different and is selected from the group consisting of alkyl, aryl, cycloalkyl, aralkyl, fluoroalkyl, perfluoroalkyl, fluoroaryi, perfluoroaryl, fluoroaralkyl, perfluoroaralkyl, alkyl ether, aryl ether, perfluoroalkyl ether and perfluoroaryl ether; L is a divalent linking radical selected from the group consisting of alkylene, arylene, cycloalkylene, aralkylene, fluoroalkylene, perfluoroalkylene, fluoroarylene, perfluoroarylene, fluoroaralkylene, perfluoroaralkylene, alkylene ether, arylene ether, perfluoroalkylene ether, perfluoroaralkylene ether, amino alkylene, amino arylene, amino cycloalkylene, amino aralkylene, amino fluoroalkylene, amino perfluoroalkylene, amino fluoroarylene, amino perfluoroarylene, amino fluoroaralkylene, amino perfluoroaralkylene, amido alkylene, amido arylene, amido cycloalkylene, amido aralkylene, amido fluroalkylene, amido perfluoroalkylene, amido fluoroarylene, amido perfluoroarylene, amido fluoroaralkylene, amido perfluoroaralkylene, keto alkylene, keto arylene, keto cycloalkylene, keto aralkylene, keto fluoroalkylene, keto perfluoroalkylene, keto fluoroarylene, keto perfluoroarylene, keto fluoroaralkylene and keto perfluoroaralkylene; R 2 is defined as a bonding group derived from a precursor selected from the group consisting of epoxy, isocyanate, blocked isocyanate, oxazoline, carbodimide, anhydride and caprolactim ether; Z is defined as a base polymer chain attached to R 2 through a terminal or a pendant functional group selected from carboxyl, amino and hydroxyl groups; x is 0 to 2000; y is defined as 2 to 20; w is defined as 0 to 20, and the Z I R2 I I I I - ( - Si - O - ) x - , - ( - Si - O - ) y - , and - ( - Si - O - ) w - I I I I I z z units of formula A are arranged-in a random or a block structure. Filament bulk is relative. A high bulk filament can be made in several ways, for example, by modifying the fiber/filament cross section and/or crimping or texturing the fiber. Level and type of crimp applied will affect bulk. Increased filament bulk, for a given polymer type, typically provides increased cover. Exemplary bulk-enhancing filament cross sections include, without limitation, void- containing cross sections created by continuous air channels and/or closed-cell voids within the fiber and multilobal cross sections with a high modification ratio. See U.S. Patent 5,322,736, hereby incorporated by reference, for further discussion on bulk and cover. Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments which follows. Brief Description of the Drawings The invention will be described below in more detail with reference to the drawing figures, wherein: , FIGURES 1 , 2 and 3 depict the results of Taber abrasion testing of materials of the present invention as compared to those of the prior art. Detailed Description of the Preferred Embodiments As used herein, the term "base polymer" denotes a polymer to which the polydiorganosiloxane is added, resulting in the formation of a polydiorganosiloxane-base polymer copolymer. The addition of the polydiorganosiloxane to the base polymer chain modifies the properties of the base polymer. The preferred base polymer is selected from the group consisting of polyamide, polyester and copolymers thereof. "Polymer chain" denotes the linear chain of recurring monomer units that forms the backbone of the base polymer. "Graft copolymer" denotes a copolymer wherein the base polymer chain segments are grafted onto the polydiorganosiloxane chain in random or block order. In other words, the -L-R 2 - bonding sites are distributed in random or block order along the polydiorganosiloxane chain according to the general formula . . . . XXXXXXXXXX . . . . or . . . . XXXXXXXXX . . . . Y Y YYY Y Y YYY Y Y YYY . . . (random) (block) The random structure is preferred since it permits the variation of structural parameters such as the effective molecular weight between the reactive Si sites depending upon the desired properties of the copolymer. The more regular spacing between the -L-R 2 - bonding sites also allows for more uniform variation of the effective molecular weight. "Polymeric fibrous structure" denotes a polymer or copolymer which has been formed into a continuous filament (single or multiple) of a running or extremely long length, or cut or otherwise short fiber known as staple, or a material which includes such a formed polymer or copolymer. An example of a polymeric fibrous structure is a textile component such as a tape, fiber, yarn, or other profile which typically has been tufted, woven, or otherwise constructed into fabric suitable for final use in apparel or home furnishings (e.g., as floor covering or upholstery fabric), or woven into a fabric for use in seatbelts, or constructed into cord used for tire reinforcement. "Polyamide" denotes nylon 6, nylon 66, nylon 4, nylon 12 and other polymers that contain the -(C-NH)- || O structure along with the (CH 2 ) X chain as described in Cook, J., Handbook of Textile Fibres, Merrow Publishing Co., PP. 194-327 (1984). Nylon 6 and 66 are preferred. "Polyester" denotes polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene napthalate (PEN), polyalkylene adipate, polyesters of dihydric phenols, liquid crystal polymers and other polymers containing the ester repeating unit as described in Encyclopedia of Polymer Science and Engineering, Vol. 12, pub. by John Wiley & Sons, Inc., pp. 1 -300 (2d ed. 1989). PET is preferred. According to the present invention, there is provided a high bulk filament comprised of a particular polymer. High bulk filament is a relative term used to describe a fiber having a high level of entrapped air within the fiber, as with void- containing fiber, and/or between the fibers as with highly shaped and/or crimped fiber. Bulk is typically a function of filament crimp or texture level and type, percentage of void space and/or modification ratio (for multilobal filament), and how the fiber packs together within the fibrous assembly. Increased filament crimp or texture, increased void space and/or increased modification ratio (or "shaped" fiber) all lead to increased filament bulk which, for a given polymer type, typically provides increased cover. With void-containing fiber cross sections, whether created by continuous air channels and/or closed-cell voids within the fiber, the level of voids by volume (% void content or % void volume) ranges from about 5 to 25%, more preferably from about 8 to 20%, and most preferably from about 10 to 15%. For crimped fiber, the level of filament crimp ranges from about 12 to 30 percent crimp elongation after boil (%CEAB, Skein Method), more preferably in the range of from about 19 to 28% CEAB, and most preferably in the range of from about 24 to 26% CEAB. The skein method is as follows. Yarn to be tested is conditioned for two hours at 65% relative humidity (RH) and about 21 °C. A 6- wrap skein of 9 meters total length is created with a conventional denier reel. The skein is submerged in a pot of boiling, distilled water for 30 minutes. The pot is drained and the skein is placed in a centrifuge for approximately one minute. The skein is removed from the centrifuge, placed on a tray and dried in an oven set at 150°C+5°C for ten minutes. The skein is removed and allowed to condition on the tray for one hour at 65% RH and about 21 °C. The skein was then hung on the upper retaining pin of a conventional recovery board, graduated in centimeters from 0 to 100. A pretension weight of about 20.2+1 g was hung at the lower end of the skein. After 30 seconds, the yarn was marked at the 50 cm point (considered the zero point) on the scale. Immediately thereafter, the 5062+25g weight is attached to the pretension weight. After 30 seconds, the distance in cm that the marked yarn has moved below the zero point is recorded and identified as L. The %CEAB is then calculated as follows: %CEAB = L(extended length) X 2. An average of about five samples is taken. A preferred high bulk filament is provided by the trilobal filament described in U.S. Patent 5,322,736, preferably comprised of a copolymer as described in EP 0 703 938. This high bulk filament is both highly shaped (multi-lobed in cross section) and void-containing (axially extending voids in the lobes), with preferably, a modification ratio in the range of from about 2.4 to 5.0 and a void content in the range of from about 5 to 15% by volume (% void volume). "Modification ratio" is a well-known measure of the cross section of a multilobal filament and is defined, for example, in U.S. Patents 4,492,731 and 5,322,736. Exemplary filament cross sections and bore groups used to make same can be seen in the drawing figures of the latter patent. More particularly and as shown in Figures 1 and 4 of the latter patent, "modification ratio" means the ratio of the radius R2 of the circumscribed circle to the radius R1 of the inscribed circle. As previously stated, the highly shaped cross section of the preferred filament of the invention has a modification ratio ranging from about 2.4 to 5.0, preferably at least 2.5, more preferably in the range of about 2.7 to 4.5, most preferably in the range of about 2.7 to 3.3. According to a preferred embodiment of the present invention, the polydiorganosiloxane is a functionalized (preferably epoxidized) polydimethylsiloxane and it is substituted at a concentration of from about 0.20 to about 0.40 of the weight of the base polymer to which it is attached. Higher concentrations may be preferred for certain applications, such as ropes and cordage. EXAMPLE 1 A nylon 6 polymer was formed into conventional nylon 6 filament in accordance with the following specification targets. Nylon 6 formic acid viscosity (FAV), about 56 (ASTM D 789-97, using 5.5g nylon 6 sample in 50 ml formic acid solution and a 350 bore Cannon-Fenske viscometer, commercially available from Cannon Corporation, in lieu of Brookfield viscometer); Polymer extrusion temperature, about 250°C; Undrawn spinning speed, about 1000 meters per minute; Undrawn bundle denier, about 2500 grams per 9000 meters; Spin finish percent wet pick-up, about 6.0%; Drawn and textured to about 16.7 denier per filament (dpf) or about 1000 total denier; CEAB (crimp elongation after boil), about 19.0%; Nylon 6 masterbatch containing anatase titanium dioxide was added prior to extrusion to achieve a concentration of about 0.25% Ti0 2 in the nylon 6 polymer. Spinnerette dies had a cross section similar to Figure 6 of U.S. Patent 5,322,736, target modification ratio of about 3.0 and target void content of 8 to 12 % void volume. Samples 1 through 4 of Table 1 represent control carpets of increasing filament weight, respectively, made from the filament. All carpet samples were tufted on a tenth (1/10) gauge tufting machine, pre-steamed in a vertical steamer at about 100°C for about 3 minutes, dried in a dryer, continuously dyed a medium gray color, followed by post-steaming in a vertical steamer at about 100°C for about 5 minutes, and dried. The dyed carpets were machine coated with a standard SBR (styrene-butadiene-rubber) latex and tip sheared. These carpet samples 1 through 4 were then subjected to Taber abrasion testing using test method B of SAE-J1530 AUG 94. These carpet samples form the control samples for this example. A second nylon 6 polymer was made and formed into filament in the same manner, except that a nylon 6 masterbatch containing about 7.2 weight percent of an epoxidized polydimethylsiloxane was added prior to extrusion to achieve a concentration of about 0.25 weight percent of the siloxane in the final nylon 6 polymer to be extruded into filament. [The polydiorganosiloxane can be added via direct injection rather than by masterbatch if desired.] The epoxidized polydimethylsiloxane utilized was I I I I CH 3 SiO SiO SiO Si CH 3 X O CH∑ CH I O CH 2 wherein x = 670 and y = 6. Samples 5 through 8 of Table 1 represent carpets of increasing filament weight made from the modified nylon 6 filament, and correspond in weight (for comparison) to control samples 1 through 4, respectively. These samples were also identically tufted, dyed, machine coated, tip sheared and subjected to Taber abrasion testing. Results for all samples, 1 through 8, are presented in Table 1. Table 1 *Control Samples As shown in FIGURE 1 , interpolation of the data from Table 1 shows that for comparable abrasion performance (cycles to failure, with the higher number representing better performance), the carpet filament weight (face weight of the carpet) can be reduced up to about 28 percent. Alternatively, for the same carpet filament weight, abrasion performance can be increased by some 200% (compare sample 8 with sample 4). The determination of cycles to failure for Taber abrasion testing is subjective since the technician stops the test when the carpet backing first becomes visible to the technician. Therefore, to more objectively quantify the fiber loss from wear (e.g., Taber cycles), the rate at which the carpets lose filament face weight is used to predict the increase in Taber cycles for a given weight loss. See FIGURE 2, the data points for which are set forth in Table 2. Table 2 EXAMPLE 2 Samples A and B for this example are carpets made in accordance with, respectively, Samples 4 and 8 of Example 1. Sample C carpet was made in accordance with Example 1 , Sample 4, except that the carpet face filament was topically treated by spraying with a 43.57 weight percent aqueous solution of PE-30, a polyethylene wax emulsion commercially available from ACT Technologies, Inc., followed by drying. Sample D carpet was made in accordance with Example 1 , Sample 4, except that the carpet face filament was topically treated by application with a spray, as described in U.S. Patent 3,511 ,699, followed by drying at about 100°C for 5 minutes. The topical spray comprised a solution of 0.27 g polydimethylsiloxane dissolved in 40 ml of hexane, in the absence of a catalyst. Sample E carpet was made like Sample D, except that the topical treatment solution comprised a solution of 0.21 g polydimethylsiloxane dissolved in 40 ml of hexane in the presence of 0.012 g ( 5% based on the weight of polydimethylsiloxane) of dissolved dibutyl tin dilaurate as a catalyst. Samples A through E were steam cleaned twice with ALL IN ONE detergent (Mfg. by certified Chemical and Equipment Co., Cleveland, OH) diluted 3.12 cc/liter of water in accordance with AATCC Test Method 171-1989 and allowed to dry horizontally. Eight additional carpet cleanings were performed on the samples in the same manner as above to determine the durability of treatment. Results are presented in FIGURE 3 and Table 3. It will be seen that, as the number of cleanings increased, the durability of sample B (present invention) was far superior to that of the other samples tested. The data was interpolated to reflect a constant weight loss or 1.2 g for each sample. Table 3 Taber Cycles to Constant Weight Loss (1.2g) Sample Identification EXAMPLE 3 A 1075 denier, 80 filament nylon 6 yarn, like that utilized in samples 5 through 8 of Example 1 , was tufted into a carpet at a nominal 305 g/m 2 filament face weight and with a pile height of 0.635 cm . The carpet was dyed a medium beige color, pre-coated on the back side with polyethylene, coated with a conventional automotive secondary backing material, and tip sheared. The carpet was molded into a standard automotive flooring article and tested for Taber cycles to failure and fiber loss at 600 cycles from each of the foot wells (SAE-J1530 - method B AUG 94). Results are set forth in Table 4, below. Table 4 The carpet was submitted for evaluation to a panel of experts in the field of automotive interiors. This lower filament weight carpet was deemed to be aesthetically acceptable with respect to cover for an automotive application and also exhibited excellent abrasion resistance. From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, make various changes and modifications of the invention to adapt it to various usages and conditions.

Claims: We claim: 1. A polymeric filament characterized by high bulk and comprising a polydiorganosiloxane-base polymer copolymer. 2. The filament of claim 1 wherein the high bulk is provided by said filament having a total cross-sectional area containing from about 5 to 25 percent void area. 3. The filament of claim 1 wherein the high bulk is provided by said filament having a crimp level in the range of from about 12 to 30 %CEAB. 4. The filament of claim 1 wherein the high bulk is provided by said filament having a cross-sectional shape with a modification ratio ranging from about 2.4 to 5.0. 5. The filament of claim 4 wherein said modification ratio ranges from about 2.7 to 3.3. 6. The filament of claim 4 wherein said filament is multi-lobal in cross-section. 7. The filament of claim 4 wherein said filament is further characterized by having a total cross-sectional area containing from about 5 to 25 percent void area. 8. The filament of claim 7 wherein said filament is multi-lobal in cross-section with a plurality of axially extending voids. 9. The filament of claim 8 wherein said filament comprises a plurality of lobes, each of said lobes having at least one axially extending void therethrough. 10. The filament of claim 1 wherein the polydiorganosiloxane-base polymer copolymer has a structure represented by the following formula A: z I R 2 Ri Ri Ri L Ri I I I I I Ri - Si - O - ( - Si - O - ) x - ( - Si - O - ) y - (Si - O - ) w - Si - I I I I I Ri Ri L L L L Ri I I 1 1 R 2 R 2 I I 1 1 Z Z (A) wherein each of Ri is the same or different and is selected from the group consisting of alkyl, aryl, cycloalkyl, aralkyl, fluoroalkyl, perfluoroalkyl, fluoroaryi, perfluoroaryl, fluoroaralkyl, perfluoroaralkyl, alkyl ether, aryl ether, perfluoroalkyl ether and perfluoroaryl ether; L is a divalent linking radical selected from the group consisting of alkylene, arylene, cycloalkylene, aralkylene, fluoroalkylene, perfluoroalkylene, fluoroarylene, perfluoroarylene, fluoroaralkylene, perfluoroaralkylene, alkylene ether, arylene ether, perfluoroalkylene ether, perfluoroaralkylene ether, amino alkylene, amino arylene, amino cycloalkylene, amino aralkylene, amino fluoroalkylene, amino perfluoroalkylene, amino fluoroarylene, amino perfluoroarylene, amino fluoroaralkylene, amino perfluoroaralkylene, amido alkylene, amido arylene, amido cycloalkylene, amido aralkylene, amido fluroalkylene, amido perfluoroalkylene, amido fluoroarylene, amido perfluoroarylene, amido fluoroaralkylene, amido perfluoroaralkylene, keto alkylene, keto arylene, keto cycloalkylene, keto aralkylene, keto fluoroalkylene, keto perfluoroalkylene, keto fluoroarylene, keto perfluoroarylene, keto fluoroaralkylene and keto perfluoroaralkylene; R 2 is defined as a bonding group derived from a precursor selected from the group consisting of epoxy, isocyanate, blocked isocyanate, oxazoline, carbodimide, anhydride and caprolactim ether; Z is defined as a base polymer chain attached to R 2 through a terminal or a pendant functional group selected from carboxyl, amino and hydroxyl groups; x is 0 to 2000; y is 2 to 20; w is 0 to 20; and the Z I R 2 I - ( - Si - O - ) x - , - ( - Si - O - ) y - , and - ( - Si - O - ) w - I I I Ri L L I I R 2 R 2 I I Z Z units of formula A are arranged-in a random or a block structure. 11. The filament of claim 10 wherein Z is selected from the group consisting of polyamide, polyester, polyurea, polyimide, polycarbonate, polyether, polyarylate, polyether ester, telechelic functionalized polystyrene and telechelic functionalized polyolefin. 12. The filament of claim 10 wherein the precursor for R 2 is selected from the group consisting of epoxy, isocyanate, blocked isocyanate, oxazoline, carbodiimide, anhydride and caprolactim ether. 13. The filament of claim 10 wherein x ranges from 25 to 1500. 14. The filament of claim 10 wherein y ranges from 2 to 10. 15. An article comprising the filament of claim 1. 16. A carpet comprising the filament of claim 1 as face fiber. 17. The filament of claim 10 characterized by at least three lobes in cross section, shaped such that the cross section has a modification ratio ranging from about 2.4 to 5.0; a void content in cross section ranging from about 5 to 25 percent; a crimp level ranging from about 12 to 30 % CEAB; and wherein R1 is methyl; the precursor for R2 is selected from the group consisting of epoxy, blocked isocyanate and anhydride; x ranges from 25 to 1500; y ranges from 2 to 10; and z comprises a polyamide or a polyester. 18. The filament of claim 17 wherein that portion of the copolymer structure excluding base polymer chain z comprises from about 0.20 to about 0.40 percent of the weight of base polymer z. 19. An article comprising the filament of claim 17. 20. A carpet comprising the filament of claim 17.

Inventors: BOYLE JOHN BERNARD, BOYLE, JOHN, BERNARD
Applicants: HONEYWELL INT INC, HONEYWELL INTERNATIONAL INC.
Application year: 2001
Main classification: D01F6
IPC codes: D01D5, D01F6