Patent Publication Number: US-2018051402-A1

Title: Blowable natural down alternative

Description:
BACKGROUND 
     The present disclosure relates to natural down-like insulation fill materials. More particularly, it relates to a blowable synthetic material comparable to natural down in various performance attributes, methods for manufacturing the same, and articles incorporating the synthetic material as an insulation filler. 
     A wide variety of natural and synthetic filling material for thermal insulation applications, apparel such as outerwear and accessories (e.g., jackets, stocking caps, gloves, etc.), sleeping bags, and bedding articles (e.g., comforters, pillows, quilts, bedspreads, etc.) are known. Natural feather down has found wide acceptance for thermal insulation applications, primarily because of its outstanding thermal weight efficiency, softness, and resiliency. Properly fluffed and contained within an article or garment, natural down is generally recognized as an insulation material of choice. However, natural down compacts and loses its insulating properties when it becomes wet and can exude a rather unpleasant odor when exposed to moisture. Moreover, the cost of natural down has increased dramatically over the past several years. 
     To address the above concerns, numerous attempts have been made to prepare synthetic fiber-based structures or materials having the characteristics and structure of natural down. Natural down is very difficult to replicate due to its unique structure and properties; namely, warmth per weight, compressibility, and compression recovery. Further, natural down is readily handled or distributed by the conventional blowing equipment (e.g., a machine or apparatus configured to transport loose fill material via an airstream) utilized by many garment and bedding manufacturers. Unfortunately, prior efforts to develop a feasible replacement material have not met one or more of these desired qualities of natural down. For example, some synthetic fiber-based insulation materials (e.g., the materials described in U.S. Pat. Nos. 4,588,635 and 4,992,327) may exhibit warmth per weight properties akin to natural down, but are not easily incorporated as a replacement to down and are not blowable (i.e., cannot be acceptably handled or transported by conventional blowing equipment). Conversely, other synthetic-based insulation materials appropriate for garments and the like purport to be blowable, but do not necessarily compare to natural down in terms of at least warmth and/or compression recovery (e.g., the materials described in U.S. Pat. Nos. 6,329,052 and 7,682,693). 
     In light of the above, a need exists for a blowable synthetic insulation material comparable to natural down in terms of warmth and/or compression/recovery. 
     SUMMARY 
     Some aspects of the present disclosure are directed toward a blend of polyester staple fibers and corresponding insulation fill materials useful as a replacement for natural down in various articles such as outdoor apparel (jackets, hats, gloves, etc.), sleeping bags, and bedding (comforters, pillows, etc.). The polyester staple fiber blend includes a plurality of first polyester staple fibers, a plurality of second polyester staple fibers, and optionally a plurality of third polyester staple fibers. An average Denier of each of the second polyester staple fibers is greater than an average Denier of each of the first polyester staple fibers. Where provided, an average Denier of each of the third polyester staple fibers is greater than an average Denier of each of the second polyester staple fibers. Further, a length of substantially all the fibers of the blend is in the range of 16-63 mm, alternatively in the range of 20-40 mm. Additionally, at least a majority, optionally substantially all, of the fibers of the blend are opened. In some embodiments, some or substantially all of the fibers of the blend are crimped; in other embodiments, some or substantially all of the fibers of the blend include a lubricant (e.g., are siliconized). In one non-limiting embodiment, the blend of polyester staple fibers includes 20-30 weight percent of not greater than about 1 Denier polyester staple fibers, 20-30 weight percent of greater than about 1 up to about 2 Denier polyester staple fibers, and 40-60 weight percent of greater than about 2 Denier polyester staple fibers, with substantially all of the fibers of the blend each having a length in the range of 20-40 mm. The polyester staple fiber blends of the present disclosure are blowable and may exhibit superior performance in terms of warmth, compression/recovery, and wash durability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified cross-sectional view of an article including a polyester staple fiber blend in accordance with principles of the present disclosure; 
         FIG. 2  is a schematic illustration of a system for manufacturing the polyester staple fiber blends in accordance with principles of the present disclosure; and 
         FIGS. 3 and 4  are graphs illustrating the results of Warmth/Heat Transfer Resistance testing described in the Examples section. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present disclosure provide an insulation material comprised of a blend or mixture of polyester staple fibers. The blend includes at least two different polyester staple fiber formats or types, optionally three different polyester staple fiber formats or types. Further, the blend is blowable (e.g., the fibers of the blend are collectively loose filled or opened) and exhibits warmth or heat transfer resistance characteristics comparable to natural down. In some embodiments, the blowable insulation material of the present disclosure is comprised essentially of the blend of polyester staple fibers, and may exhibit superior performance in terms of warmth (e.g., warmth per thickness (or thermal resistivity), and/or warmth per basis weight (or thermal weight efficiency)), compression/recovery, and/or wash durability. 
     The fibers of the polyester staple fiber blends of the present disclosure are selected from one of three polyester staple fiber formats or types. For ease of explanation, the fiber formats or types are referred to as Fiber Format A, Fiber Format B, and Fiber Format C. While the fibers of the three Fiber Formats can have similarities (e.g., base polymer composition and length), Fiber Format A, Fiber Format B, and Fiber Format C differ from one another at least in terms of average Denier as described in greater detail below. 
     For example, all of the polyester staple fibers of the blend (and thus the fibers of each of the Fiber Formats A, B and C) can be single component in nature, formed from a similar or identical polyester material such as, but not limited to: polyethylene terephthalate (PET). In some embodiments, the fibers of each of the three Fiber Formats are PET. In other embodiments, the fibers of one of the Fiber Format can have a polyester formulation differing from the polyester formulation of the other Fiber Formats. In other embodiments, the fibers may include other synthetic fibers, including, but not limited to, polymers or combinations of: polyesters, polyamides, polyolefins, polyacrylates, and polyaramids. 
     Further, substantially all (e.g., at least 95%, optionally at least 98%, optionally at least 99%) of the polyester staple fibers of the blend (and thus the fibers of Fiber Formats A, B and C) are cut to a length in the range of 16-63 mm, optionally in the range of 20-40 mm, optionally on the order of 32 mm. It has been surprisingly found that the fiber lengths of the present disclosure beneficially render the blend of polyester stable fibers, and thus the insulation materials of the present disclosure, conducive to handling or distribution by conventional blowing equipment. 
     An additional, optional similarity of the fibers comprising the polyester staple fiber blend (and thus the fibers of Fiber Formats A, B and C) relates to crimping. For example, a majority, optionally substantially all (e.g., at least 95%, optionally at least 98%, optionally at least 99%), of the polyester staple fibers of the blend (and thus a majority or substantially all of the fibers of Fiber Formats A, B or C comprising the blend) are crimped (e.g., two-dimensional mechanical crimp, spiral crimp, etc.), for example having 1-10 crimps/cm. In other embodiments, substantially all of the fibers of at least one of the Fiber Formats comprising the polyester staple fiber blend are crimped fibers, whereas a majority or substantially all of the fibers of another Fiber Format comprising the polyester staple fiber blend are not crimped. In yet other embodiments, substantially all of the fibers of the polyester staple fiber blend are not crimped. 
     An additional, optional similarity of the fibers comprising the polyester staple fiber blend (and thus the fibers of Fiber Formats A, B and C) relates to lubricants, and in particular the addition of a lubricant or slickening agent (e.g., a silicone slickener, aqueous solutions of organopolysiloxanes, emulsions of polytetrafluoroethylene, non-ionic surfactants, etc.) for water resistance, improved feel and/or handling, and antistatic properties. The lubricant can be applied (e.g., spray coated) on to an exterior surface of the polyester staple fibers, or can be added to the polyester material during formation of the corresponding fibers (e.g., at the spinning stage prior to drawing). With this in mind, in some embodiments a majority, optionally substantially all (e.g., at least 95%, optionally at least 98%, optionally at least 99%), of the polyester staple fibers of the blend (and thus a majority, optionally substantially all, of the fibers of Fiber Formats A, B or C comprising the blend) include a lubricant (e.g., are siliconized polyester fibers). In other embodiments, substantially all of the fibers of at least one of the Fiber Formats comprising the polyester staple fiber blend include a lubricant, whereas a majority or substantially all of the fibers of another Fiber Format comprising the polyester staple fiber blend do not include a lubricant. In yet other embodiments, substantially all of the fibers of the polyester staple fiber blend do not include a lubricant. 
     As mentioned above, while Fiber Formats A, B and C can have certain similarities, the fibers of Fiber Formats A, B and C differ from one another at least in terms of average Denier or cross-dimensional size. In particular, the polyester staple fibers of Fiber Format A have a Denier of not greater than about 1 Denier, optionally a Denier in the range of about 0.5 to not greater than about 1 Denier, optionally on the order of 0.7 Denier. The polyester staple fibers of Fiber Format B have a Denier in the range of greater than about 1 Denier to not greater than about 2 Denier, optionally on the order of 1.4 Denier. The polyester staple fibers of Fiber Format C have a Denier greater than about 2 Denier, optionally in the range of about greater than 2 Denier to 7 Denier, optionally on the order of 3 Denier. 
     An additional, optional difference between the fibers of at least one of the Fiber Formats relates to structure. In particular, some of the fibers comprising the polyester staple fiber blend can be solid, whereas others of the fibers comprising the polyester staple fiber blend can be hollow or tubular. For example, a majority, optionally substantially all (e.g., at least 95%, optionally at least 98%, optionally at least 99%), of the fibers of a first one of the Fiber Formats comprising the blend (i.e., Fiber Format A, B or C) are solid; whereas a majority, optionally substantially all (e.g., at least 95%, optionally at least 98%, optionally at least 98%), of the fibers of a second one of the Fiber Formats comprising the blend (i.e., Fiber Format A, B or C) are hollow. By way of one non-limiting example, some polyester staple fiber blends in accordance with principles of the present disclosure consist include fibers of Fiber Format A and Fiber Format B is solid form, and fibers of Fiber Format C in hollow form. In other embodiments, substantially all of the fibers of the blend are hollow regardless of Fiber Format; in yet other embodiments, substantially all of the fibers of the blend are solid regardless of Fiber Format. Fibers can be circular or other shapes in cross sections such as triangular. 
     With the above characteristics of Fiber Formats A, B and C in mind, the polyester staple fiber blends of the present disclosure comprise, optionally consist essentially of, fibers from at least two, optionally all, of Fiber Formats A, B, and C. In some embodiments, the polyester staple fiber blends of the present disclosure are comprised of 20-30 weight percent of Fiber Format A, 40-60 weight percent of Fiber Format B, and 40-60 weight percent of Fiber Format C. 
     Regardless of an exact composition, the polyester staple fiber blends of the present disclosure can be characterized as loose fill, with at least a majority of the fibers comprising the blend being opened (as commonly understood to those of ordinary skill in the art). That is to say, at least a majority, alternatively at least about 70%, and in other optional embodiments substantially all (e.g. at least 95%, alternatively at least 98%, alternatively at least 99%), of the fibers comprising the blend are separated, individualized and unbonded relative to one another. The “opening” of the fibers of the polyester staple fiber blend means that the fibers are worked upon such that the individual fibers of the blend are separated from each other and are not clustered. Opening of the fibers of the staple fiber blend can be accomplished by various methods known in the art as described in greater detail below. 
     In some embodiments, the insulation materials of the present disclosure consist substantially, alternatively solely, of the polyester staple fiber blend as described above. In other embodiments, the insulation materials can include one or more components in addition to the polyester staple fiber blend, such as other synthetic fibers, natural fibers, natural down, and fiber clusters. Other possible additives envisioned by the present disclosure include benefitting additives such as chopped sponge, anti-microbials, abrasives, odor absorbing particulate, adhesive/binder particulate (e.g., heat activatable, moisture transporting particulate, heat conducting particulate (e.g., inorganic, metallic, crushed gemstones), radiation blocking (UV/visible/IR), detergent/soap, wetting agents, microencapsulants (phase change materials, fragrance, essential oils, etc.), flame retardants, etc. 
     The insulation materials described above can be incorporated into various articles. For example,  FIG. 1  is a simplified view of a portion of an article  10  in accordance with principles of the present disclosure. The article  10  can assume a variety of forms, such as apparel including outerwear and accessories (e.g., jackets, stocking caps, gloves, etc.), sleeping bag, bedding articles (comforters, pillows, quilts, bedspreads, etc.), and generally includes a quantity or volume of the blend of polyester staple fibers  12  as described above contained within a pocket  14  formed by an outer shell or liner  16  (e.g., fabric, film, etc.). In some embodiments, construction of the article  10  includes dispensing or filling the blend of polyester staple fibers  12  into the pocket  14  with a conventional blowing device (i.e., the blend of polyester staple fibers  12  is delivered into the pocket  14  via a forced airstream). 
     Various methods can be employed in accordance with principles of the present disclosure to manufacture the polyester staple fiber blends described above. In general terms, desired quantities of fibers of Fiber Format A, Fiber Format B and/or Fiber Format C, in accordance with the weight percent selected for the resultant blend, are obtained. The polyester fibers can be obtained, for instance, by conventional spinning/drawings or extrusion techniques as known in the art, and can be cut to the lengths described above. The so-obtained fibers may be crimped and may include a lubricant as described above. Regardless, the fibers are then mixed and opened to produce the polyester staple fiber blend of the present disclosure and useful as a blowable insulation material. 
     One non-limiting example of a system  20  (and corresponding method) for producing the polyester stable fiber blends of the present disclosure is provided in  FIG. 2 . Raw polyester staple fibers are received at a loading station  22 . The loading station  22  can include three (or more) pre-feeder substations  22   a - 22   c  each including a weighing pan (as known in the art), one for each of the Fiber Formats to be included with the resultant blend. For example,  FIG. 2  reflects fibers of Fiber Format A being loaded on to the first pre-feeder substation  22   a,  fibers of Fiber Format B being loaded on to the second pre-feeder substation  22   b,  and fibers of Fiber Format C being loaded on to the third pre-feeder substation  22   c.  The raw polyester staple fibers can be supplied in bale form, can be formed substantially in-line with the system  20 , etc. Once a desired quantity of the each of the Fiber Formats A, B and/or C has been obtained (e.g., based on weight), the quantities are dispensed from the corresponding pre-feeder substation  22   a - 22   c  on to a conveyor  24 . The conveyor  24  operates to deliver the quantities of fiber to a mixing station  26 . The mixing station  26  can assume include various mechanisms appropriate for effectuating mixing of the fibers as known in the art, such as a turbulent airstream. The mixing station  26  can further operated to effectuate coarse opening of the fibers. 
     The mixed blend of polyester staple fibers (identified generally at  28  in  FIG. 2 ) is then fed to a fine opening station  30  configured to effectuate more complete or full opening of substantially all of the fibers of the blend. The fine opening station  30  can assume various forms and can incorporate various mechanisms for “working” or opening the fibers, such as rotating or vibrating pins or shafts, compressed air, etc. The systems and methods of the present disclosure can further include additional opening stations downstream of the fine opening station  30  and that utilize other fiber opening techniques. In other embodiments, the mixing station  26  alone interfaces with the fibers to sufficiently generate desired openness. 
     The blend of opened polyester staple fibers (referenced generally at  32  in  FIG. 2 ) is then fed to one or more gathering stations  34 . The gathering station(s)  34  can assume various forms, and in some embodiments each include a chute  36  (or other feeding apparatus) and a carding machine  38  (e.g., a Double Doffer carder). The so-gathered blend of polyester staple fibers is then prepared for delivery to an end user/manufacturer (e.g., packaged or bagged) for use as a blowable insulation fill material. 
     EXAMPLES AND COMPARATIVE EXAMPLES 
     Objects and advantages of the present disclosure are further illustrated by the following non-limiting examples and comparative examples. The particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the present disclosure. 
     Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of this specification are by weight. 
     A first example of a polyester staple fibers blend (“Example Blend A”) in accordance with principles of the present disclosure was prepared and consisted of: 1) 30 weight percent of crimped, siliconized, solid polyester staple fibers of 0.7 Denier and an average length of 32 mm (e.g., Fiber Format A); 2) 30 weight percent of crimped, solid polyester staple fibers of 1.4 Denier and an average length of 38 mm (e.g., Fiber Format B); 3) 40 weight percent of crimped, siliconized, hollow polyester staple fibers of 3 Denier and an average length of 32 mm (e.g., Fiber Format C). 
     A second example of a polyester staple fibers blend (“Example Blend B”) in accordance with principles of the present disclosure was prepared and consisted of: 1) 60 weight percent of crimped, siliconized, solid polyester staple fibers of 0.7 Denier and an average length of 32 mm (e.g., Fiber Format A); 2) 20 weight percent of crimped, siliconized, hollow polyester staple fibers of 3 Denier and an average length of 32 mm (e.g., Fiber Format B); 3) 20 weight percent of crimped, siliconized, hollow polyester staple fibers of 7 Denier and an average length of 32 mm (e.g., Fiber Format C). 
     Blowability Testing 
     Blowability (or loose fill properties) was tested by evaluating handling of the material by a conventional blowing machine, and in particular a natural down filling or blowing machine available from B&amp;B di Borsio of Tarzo, Italy under the trade designation “Alan PE”. The Alan PE blowing machine includes an inlet or feeding chamber and an outlet or injector reducer. Further, the Alan PE blowing machine provides for variable speeds of operation, and includes a variable speed controller dial with eleven speed setting (“0” being the lowest speed setting, and “10” being the highest). Handful-sized samples (approximately 13 grams of material was divided into 10 handful size samples (1-2 grams each sample)) of Example Blend A were prepared. A first one of the samples was placed in the feeding chamber, and the variable speed controller was set to the highest velocity (“10”). The blowing machine was then activated and a manual determination made as to whether or not the sample passed through the machine (e.g., exited the injector reducer) without plugging (e.g., signs of reduced air output, ability to see light through the injector reducer, etc.). If it was determined that the sample passed through without plugging, Example Blend A was designated has having been successfully blown at the particular speed setting; the variable speed controller setting was then reduced by 1 increment, and the steps repeated with a new the samples. If it was determined that plugging occurred, the blowing machine was first cleared of the blockage, and the process repeated three additional times (“trials”) at the same speed setting. If all three trials did not result in plugging, Example Blend A was designated as being blowable (i.e., successfully blown) at the particular speed setting; the variable speed controller setting was then reduced by 1 increment, and the steps repeated with a new sample. If two consecutive instances of plugging at a particular speed setting were detected, Example Blend A was designated as not blowable (i.e., unsuccessfully blown) at the particular speed setting or at any lower speed settings, and the testing discontinued. 
     For purposes of comparison, the above-described blowability test was performed using samples of natural down (Comparative Example 1) and using samples of an opened synthetic fiber material consisting of 3 Denier×64 mm crimped, siliconized, hollow polyester staple fibers (Comparative Example 2). Results of the blowability testing are reported in Table 1, where “S” represents that the sample in question was designated to be successfully blown (i.e., no plugging) at the corresponding velocity setting, and “U” represents that the sample in question was designated to not be successfully blown at the corresponding velocity setting. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Blowability 
               
            
           
           
               
               
            
               
                   
                 Velocity Setting 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Sample 
                 10 
                 9 
                 8 
                 7 
                 6 
                 5 
                 4 
                 3 
                 2 
                 1 
                 0 
               
               
                   
               
               
                 Comp Ex 1 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
               
               
                 Comp Ex 2 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 U 
                 U 
                 U 
                 U 
                 U 
               
               
                 Example 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 S 
                 U 
                 U 
                 U 
               
               
                 Blend A 
               
               
                   
               
            
           
         
       
     
     As reflected by the test results, Example Blend A is blowable with conventional blowing equipment, and is more readily handled in a moving airstream than 3 Denier×64 mm polyester staple fibers (that are otherwise considered highly useful as garment insulation material filler). 
     Warmth/Heat Transfer Resistance Testing 
     Warmth (heat transfer resistance, in units of Clo) of Example Blend A was measured in accordance with ASTM C518-10 (2010) as described below. The warmth properties of comparative example insulation filling materials were similarly tested. The Comparative Examples included: 
     Comparative Example 3 
     A jacket available from Nike, Inc. under the trade designation “SB 700 Down” was obtained, and the down fill material was harvested from the jacket&#39;s shell and prepared into a standard construction for assessment. The down fill material of Comparative Example 3 is advertised as a 700 fill power down. 
     Comparative Example 4 
     A jacket available from Columbia Sportswear Co under the trade designation “Men&#39;s Upper Slopes II Down Jacket” was obtained, and the down filler material was harvested from the jacket&#39;s shell and prepared into a standard construction for assessment. The down filler material of Comparative Example 4 is advertised as a 700 fill power down. 
     Comparative Example 5 
     A jacket available from The North Face (a division of VF Outdoor, Inc.) under the trade designation “Men&#39;s Nuptse Jacket” was obtained, and the down fill material was harvested from the jacket&#39;s shell and prepared into a standard construction for assessment. The down fill material of Comparative Example 5 is advertised as a 700 fill power down. 
     Comparative Example 6 
     A jacket available from The North Face (a division of VF Outdoor, Inc.) under the trade designation “Men&#39;s Iron Jacket” was obtained, and the down fill material was harvested from the jacket&#39;s shell and prepared into a standard construction for assessment. The down fill material of Comparative Example 6 is advertised as a 700 fill power down. 
     Comparative Example 7 
     A down alternative, synthetic fiber insulation fill material available from The North Face (a division of VF Outdoor, Inc.; developed in partnership with PrimaLoft, Inc.) under the trade designation “ThermoBall Powered by PrimaLoft”. The fill material of Comparative Example 7 is advertised as being equivalent to 600 fill power down. 
     Comparative Example 8 
     A down alternative, synthetic fiber insulation fill material available from PrimaLoft, Inc. under the trade designation “PrimaLoft Luxe”. 
     Comparative Example 9 
     An insulation fill material comprising a 60-40 blend of down and synthetic fibers available from PrimaLoft, Inc. under the trade designation “PrimaLoft Silver Down Blend”. The fill material of Comparative Example 9 is advertised as being equivalent to 650 fill power down. 
     Comparative Example 10 
     A natural down alternative, synthetic fiber insulation fill material available from 3M Company under the trade designation “3M Thinsulate Featherless Insulation—600” was obtained and prepared into a standard construction for assessment. The fill material of Comparative Example 10 is advertised as mimicking 600 fill power down. 
     Comparative Example 11 
     An insulation fill material comprising a 70-30 blend of down and synthetic fibers available from PrimaLoft, Inc. under the trade designation 
     “PrimaLoft Gold Down Blend”. The fill material of Comparative Example 11 is advertised as being equivalent to 750 fill power down. 
     Test specimens were prepared by quilting 200 gsm (grams per meter) loose material samples of Example Blend A and Comparative Examples 3-11 into approximately 12 inch×12 inch (30.5 cm×30.5 cm) panels with approximately 3 inch (7.6 cm) pleat spacing. First, 12 inch×12 inch (30.5 cm×30.5 cm) fabric sheets were obtained from a 104×104 thread count 1.9 oz/yd 2  (64.4 gsm) Nylon Ripstop (5 ribs per inch (2.54 cm)) fabric. Two of the fabric sheets were aligned and then sewn to one another along three of the four common edges to provide a panel forming a pocket which was then inverted prior to filling. Comparative Example test specimens using the samples of Comparative Examples 3-11 were prepared by evenly distributing the 200 gsm sample into the pocket, followed by sewing quilt lines across the panel at 3 inch (7.6 cm) increments. A first Example test specimen using a 200 gsm sample of Example Blend A was prepared in an identical manner (“Example A-1”). A second Example test specimen using a 200 gsm sample of Example Blend A was prepared by a “channel fill” method in which pre-sewing quilt lines were first formed across the panel at 3 inch (7.6 cm) increments to define four channels; the Example Blend 1 sample (200 gsm) was then filled into each of the so-formed channels (“Example A-2”). All of the test specimens were conditioned for 24 hours in a CTH room set to 21±2° C. and 50±2% RH. In some instances if the fiber blend materials had become compressed due to handling (i.e., storage or shipping) the fibers were re-lofted by hand carding. 
     The thickness of each of the test specimens was recorded, and heat transfer resistance (warmth) was calculated in accordance with ASTM C518-10 (2010). The so-obtained heat transfer resistance value for each test specimen was calculated (in units of Clo). The results of the warmth testing are reported in the graphs of  FIGS. 3 and 4 .  FIG. 3  provides a comparison of the recorded thickness and warmth values of Comparative Example 3-6 test specimens, Example Blend A-1 test specimen, and Example Blend A-2 test specimen.  FIG. 4  provides a comparison of the recorded thickness and warmth values of Comparative Examples 7-11 test specimens and Example Blend A-1 test specimen. 
     The warmth testing results indicate that Example Blend A is comparable to that of typical 700 fill power down ( FIG. 3 ). It was observed that the method of construction (direct sew (Example Blend A-1 test specimen) vs. channel fill (Example Blend A-2 test specimen)) may more substantively impact the thickness of the test panel and subsequent heat transfer resistance (Clo) results with Example Blend A as compared to the natural down Comparative Examples. In addition, the warmth testing results indicate that warmth performance of Example Blend A exceeds that of several existing synthetic fiber insulation fill materials and is comparable to that of existing natural down-synthetic fiber blend insulation fill materials ( FIG. 4 ). Example Blend A was observed as having beneficial warmth per thickness (or thermal resistivity) characteristics. 
     Compression-Recovery Testing 
     Compression-Recovery properties were measured in accordance with ASTM D6571-01 (2001) except as listed below. Test specimens were prepared pursuant to the descriptions of the Warmth/Heat Transfer Resistance Testing section above with the “channel fill” method, using samples of Example Blend A, Example Blend B, and Comparative Example 6 (natural down). 
     Compression-Recovery testing of the respective Examples and Comparative Examples began by stacking several of the corresponding test specimens between the plates of a loading device commensurate with that of ASTM D6571-01 (2001). A number of masses were then centrally and uniformly placed on the specimen stack to get the correct total mass in accordance with that of ASTM D6571-01 (2001). The initial height of the so-prepared specimen stack was measured and recorded (A). After a 24-hour test period, the height of the compressed specimen stack was measured and recorded (G). Percent Compression was determined as: 100 (A-G)/A. The mass was removed and the specimen stack was allowed to relax for one hour. After the one hour recovery period, the height of the specimen stack was measured and recorded, and Percent Short Term Recovery was determined as: 100 J/E. 
     The results of the Compression-Recovery Testing are reported in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Compression/Recovery 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Initial 
                 Height after 
                 Height 
                 % 
                 % Short Term 
               
               
                   
                 Height 
                 24 hours 
                 Change 
                 Compres- 
                 Compression 
               
               
                 Sample 
                 (cm) 
                 (cm) 
                 (cm) 
                 sion 
                 Recovery 
               
               
                   
               
               
                 Example 
                 9.8 
                 1.3 
                 8.6 
                 87 
                 80 
               
               
                 Blend A 
               
               
                 Example 
                 9.6 
                 1.2 
                 8.4 
                 87 
                 79 
               
               
                 Blend B 
               
               
                 Comp Ex 
                 8.5 
                 1.6 
                 6.9 
                 81 
                 77 
               
               
                 6 
               
               
                   
               
            
           
         
       
     
     Wash Durability Testing 
     Wash durability was evaluated by subjecting test specimens (described below) to the following testing. Prior to washing in a conventional automatic washing machine, a thickness and warmth value (in units of Clo as tested and calculated by ASTM C518-10 (2010)) of the test specimen was measured and recorded. The washing machine settings were selected as “super load fill level”, a cold water wash, cold water rinse, delicate cycle, and regular soil wash setting. 16 grams of powdered laundry detergent (TIDE. Procter &amp; Gamble Co.) was added to the washing machine&#39;s tub, and the washing cycle initiated. After allowing the tub to fill with water for 20-30 seconds, 3-6 test specimens were added to the washing machine&#39;s tub along with three ballast items (pre-washed and cleaned fabric bath towels). When the wash cycle was complete, the entire load was transferred to a conventional automatic clothes dryer. The dryer was set to “delicate”. Three clean tennis balls (pre-washed before use) were then added to the dryer. After 60 minutes drying time, the test specimen was removed. Thickness and warmth value of the washed/dried test specimen was measured and recorded after 24 hours of conditioning in the CTH room set to 21±2° C. and 50±2% RH. An exterior of the washed/dried test specimen was visually evaluated along at least one channel of the specimen and rated on a scale of 1-5 according to the guidelines of Table 3. Further, the washed/dried test specimen was cut open and an interior of at least one channel of the test specimen was visually evaluated on a scale of 1-5 according to the guidelines of Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Rating System 
               
            
           
           
               
               
            
               
                 Rating 
                 Description 
               
               
                   
               
               
                 1 
                 Channel has large areas with no material, and feels stiff or hard 
               
               
                   
                 to the touch, little or no loft 
               
               
                 2 
                 Channel has multiple small areas with little or no material, and 
               
               
                   
                 feels less stiff with potential balling or pilling of the material, 
               
               
                   
                 has some loft 
               
               
                 3 
                 Channel has few areas missing material with some areas that 
               
               
                   
                 might be low on material, feels moderately soft with minor 
               
               
                   
                 balling or piling, has good loft 
               
               
                 4 
                 Channel has few areas with low or missing material, feels soft 
               
               
                   
                 with minor balling, has good loft 
               
               
                 5 
                 Channel has no areas with low or missing material, feels 
               
               
                   
                 extremely soft with no noticeable balling, has natural down- 
               
               
                   
                 like loft 
               
               
                   
               
            
           
         
       
     
     Test specimens for Wash Durability Testing were prepared pursuant to the descriptions of the Warmth/Heat Transfer Resistance Testing section above, using samples of Example Blend A and Comparative Example 8. The results of the Wash Durability Testing are reported in Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Wash Durability Testing 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Thickness 
                 Warmth 
                 Rating - 
                 Rating - 
               
               
                 Sample 
                 (cm) 
                 (Clo) 
                 External 
                 Internal 
               
               
                   
               
               
                 Example Blend A before 
                 4.42 
                 5.36 
                 — 
                 — 
               
               
                 wash/dry 
               
               
                 Example Blend A after 
                 3.52 
                 4.49 
                 5 
                 5 
               
               
                 wash/dry 
               
               
                 Comp Ex 8 before wash/dry 
                 4.14 
                 5.02 
                 — 
                 — 
               
               
                 Comp Ex 8 after wash/dry 
                 2.50 
                 3.58 
                 4 
                 4 
               
               
                   
               
            
           
         
       
     
     The blowable insulation materials and corresponding blend of polyester staple fibers of the present disclosure provide an improvement over previous designs. The polyester staple fiber blends of the present disclosure are readily transported by the airstream of conventional blowing equipment utilized to fill garments and the like with natural down. Further, the polyester staple fiber blends of the present disclosure are highly comparable to typical 700 fill power down in terms of warmth and compression/recovery, including beneficial warmth per thickness (thermal resistivity) properties. Moreover, the polyester staple fiber blends of the present disclosure exhibit better performance as compared to some existing down alternative products in terms of wash durability and are hypoallergenic. 
     Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure.