Abstract:
A process for manufacturing a polymer fill, the method comprising the steps of blending polymer fibers to form a polymer fill, depositing the polymer fill onto a surface, orientating the polymer fibers in a desired orientation, heating the polymer fill, compressing the polymer fill and cooling the polymer fill. The surface carries the polymer fill from the blending step through the heating step, and wherein the polymer fill enters the compression step independent of the surface.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to the production of polymer products and particularly, to a method of manufacturing a low melt compressed polymer fill.  
       BACKGROUND OF THE INVENTION  
       [0002]     There are essentially two methods for producing a nonwoven fiber batt, a dry method and a wet method. With the wet method, there is, just as in the production of paper, an emulsion produced which consists of a liquor and fibers which are disposed crossways from which the emulsion and liquor is removed by a force of gravity and by means of suction pumps with subsequent drying units. The wet web producing method features high production speeds and a great uniformity of the web, which consists of crossways lying fibers, but on the other hand it necessitates very power consuming subsequent drying processes and apparatus.  
         [0003]     Completely dry processes for forming nonwoven fibrous batts are known and are described in the prior art. The dry method consists of applying a powdery or granular bonding agent or melting film or bonding agents to the web. These bonding agents are then melted with a heating unit and subsequently re-hardened so that the web fibers stick together.  
         [0004]     Nonwoven fabrics are now used for a variety of purposes in a number of industries. These fabrics have been made traditionally by methods such as carding, garnetting, air-laying and the like. Nonwoven webs have been made to have most of the fibers therein oriented in the machine direction; other nonwoven webs have been made to have some cross orientation; and still other webs have been produced having a randomized fiber distribution.  
       SUMMARY OF THE INVENTION  
       [0005]     The inventors of the invention have recognized these and other problems associated with the nonwoven fabrics. To this end, the inventors have invented a process for manufacturing a polymer fill, the method comprising the steps of blending polymer fibers to form a polymer fill, depositing the polymer fill onto a surface, orientating the polymer fibers in a desired orientation, heating the polymer fill, compressing the polymer fill and cooling the polymer fill. The surface carries the polymer fill from the blending step through the heating step, and wherein the polymer fill enters the compression step independent of the surface. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a perspective view of an assembly for manufacturing polymer fill according to an embodiment of the invention.  
         [0007]      FIG. 2  is a side view of a horizontally-oriented batt according to an embodiment of the invention.  
         [0008]      FIG. 3  is a top view of a vertically-oriented batt according to an embodiment of the invention.  
         [0009]      FIG. 4  is an expanded view of a compression system according to an embodiment of the invention.  
         [0010]      FIG. 5  is an expanded view of an alternate cooling system according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]     Referring to  FIG. 1 , an assembly  10  for manufacturing a nonwoven fabric  12 , such as a polymer fill, is generally shown. The polymer fill  12  is typically made of a polymer fill, as known in the field of manufacturing polymer products, and may include a blend of polymer fibers, such as polymer staple fibers  14  of different denier. Each polymer staple fiber  14  may be comprised of a polymer inner core  14   a  and a low melting point co-polymer outer sheath  14   b.    
         [0012]     Polymers suitable for the invention include polyolefins, polymers, polyamides, polycarbonates and copolymers and blends thereof. Suitable polyolefins include polyethylene, e.g., high density polyethylene, medium density polyethylene, low density polyethylene and linear low density polyethylene; polypropylene, e.g., isotactic polypropylene, syndiotactic polypropylene, blends of isotactic polypropylene and a tactic polypropylene; polybutylene, e.g., poly(1-butene) and poly(2-butene); polypentene, e.g., poly(1-pentene) and poly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl-1-pentene); and copolymers and blends thereof. Suitable copolymers include random and block copolymers prepared from two or more different unsaturated olefin monomers, such as ethylene/propylene and ethylene/butylene copolymers. Suitable polyamides include nylon 6, nylon 6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, nylon 6/12, nylon 12/12, copolymers of caprolactam and alkylene oxide diamine, and the like, as well as blends and copolymers thereof. Suitable polymers include polyethylene terephthalate, poly-butylene terephthalate, polytetramethylene terephthalate, polycyclohexylene-1,4-dimethylene terephthalate, and isophthalate copolymers thereof, as well as blends thereof.  
         [0013]     It should be noted that the above listing of suitable thermoplastic polymers is not exhaustive and other polymers known to one of ordinary skill in the art may be employed, so long as the particular combination of polymers selected to be the components of the multicomponent fiber are capable of being co-spun in a fiber extrusion process, which will depend on such factors as, for example, the relative viscosities of the thermoplastic melt. In addition, it should be noted that the polymers may desirably contain other additives such as, reaction products including, processing aids, treatment compositions to impart desired properties to the multicomponent fibers, residual amounts of solvents, pigments or colorants and the like.  
         [0014]     The assembly  10  for manufacturing a polymer fill  12  may comprise a blender  16 , a surface  18 , a first fiber-orienting machine, such as a carding machine  20 , a second fiber orienting machine, such as a second carding machine  22 , an oven  24 , a compression system  26  and a cooling system  28 . While a garnett machine is not shown, it can be appreciated that the invention may be practiced with a garnett machine in combination with carding machines  20 ,  22 , or with a garnett machine in replace of either or both carding machines  20 ,  22 . It should be noted that carding machines and garnett machines are generally known in the art.  
         [0015]     Initially, polymer staple fibers  14  undergo a blending process A. The blending process A may be carried out by placing polymer staple fibers  14  of different denier in blender  16  and mixing the polymer staple fibers  14  together to form the polymer fill  12   a . Once the blending process A has been completed, the polymer fill  12   a  may be deposited onto surface  18 , such as, for example, a conveyor belt.  
         [0016]     The polymer fill  12   a  may be subjected to a first fiber-orientating step B. The first fiber-orientating step B may include a means for orientating the polymer staple fibers  14  into a desired orientation, such as, for instance, by feeding the polymer fill  12   a  through first carding machine  20 . First carding machine  20  combs through the polymer fill  12   a  and aligns the polymer staple fibers  14  into a first desired orientation. As illustrated, first carding machine  20  orients polymer staple fibers  14  to form a substantially horizontally-oriented batt  12   b . First carding machine  20  may further include a lapping apparatus (not shown) which releases the horizontally-oriented batt  12   b  onto conveyor belt  18  in a lapping motion to form a multilayered batt  12   c , as illustrated in  FIG. 2 . As a result, first carding machine  20  deposits successive layers of polymer fill on top of each other. The number of successive layers of polymer fill depends upon the desired specification of the polymer fill  12 . For instance, if a thick polymer fill  12  is desired, several successive layers of polymer fill may be deposited on top of each other. Conversely, if a thin polymer fill  12  is desired, few successive layers of polymer fill may be deposited on top of each other. However, it can be appreciated that the horizontally-oriented batt  12   b  may be released onto conveyor belt  18  in any suitable manner, so long as the polymer staple fibers  14  remain in a generally horizontal orientation.  
         [0017]     Once polymer staple fibers  14  have been horizontally-oriented, the multilayered batt  12   c  may be subjected to a second fiber-orientating step C. The second fiber-orientating step C may include passing the multilayered batt  12   c  through a second carding machine  22 . The second carding machine  22  may be, for example, an air lay carding machine which redirects the orientation of the polymer staple fibers  14  of multilayered batt  12   c  into a second desired orientation. For example, as illustrated, second carding machine  22  orients polymer staple fibers  14  to form a substantially vertically-oriented batt  12   d , as illustrated in  FIG. 3 . During operation, the air lay machine  22  typically pulls a large volume of air through the multilayered batt  12   c , thereby causing the polymer staple fibers  14  to re-orientate. The degree of reorientation may be dependent upon the volume of air pulled within the air lay machine  22 . It can be appreciated that carding machines and air lay machines  22 , are known in the art of manufacturing polymer fill  12 .  
         [0018]     The vertically-orientated batt  12   d  may be subjected to a heat-fusing step D to fuse at least a portion of the polymer staple fibers  14  to adjacent polymer staple fibers  14 . The heat-fusing step D may be carried out by passing the vertically-oriented batt  12   d  through a means for heating the vertically-oriented batt  12   d , such as, for example, an oven  24 . In one type of oven  24 , forced air may be conducted through the vertically-oriented batt  12   d , causing the low melting point co-polymer outer sheath  14   b  to change from a solid state to a liquid state. Accordingly, heat is conducted to vertically-orientated batt  12   d  for an amount of time sufficient to cause low melting point co-polymer outer sheath  14   b  to at least partially melt, or fuse, so that upon cooling, the polymer staple fibers  14  fuse to adjacent fibers to form a heated vertically-oriented batt  12   d . It can be appreciated that the temperature of the forced air passing through oven  24  may vary depending upon the fusing temperature of the low melting point co-polymer outer sheath  14   b . Thus, oven  24  may be set to a predetermined temperature that is at least equal to the fusing point of the low melting point co-polymer outer sheaths  14   b , or may be set to a temperature above the fusing point of low melting point co-polymer outer sheath  14   b . It can be further appreciated that using an oven to heat-fuse polymer staple fibers  14  together is known in the art of manufacturing polymer fill  12 .  
         [0019]     The heated vertically-oriented batt  12   d  may be carried from oven  24  to a compression step E via conveyor belt  18 . The compression step E may be carried out by passing the heated vertically-oriented batt  12   d  through a means for compressing, or compression system  26 . Compression system  26  comprises of a set of steel rollers  32  stacked vertically, with a top steel roller  34  stacked above a bottom steel roller  36 .  
         [0020]     The top and bottom steel rollers  34 ,  36  are separated by a gap  38 . Bottom roller  36  is mounted rigidly at approximately the same elevation as conveyor belt  18 , while top roller  34  is mounted independently of bottom roller  36  by a set of jack screws  48 . The jack screws  48  are driven by an electric motor (not shown). Accordingly, top roller  34  may be adjusted vertically up and down, to increase or decrease gap  38 , by jack screws  48 .  
         [0021]     It should be noted that the calculation of gap  38  may be dependent upon several factors, including, amongst others, the rise times of reaction products in the vertically-oriented batt  12   d , the percent rise of the reaction products per unit of time, the desired characteristics of polymer fill  12 , the speed at which the vertically-oriented batt  12   d  enters the compression system  26 , and the like.  
         [0022]     As illustrated in  FIGS. 1 and 4 , conveyor belt  18  carries the vertically-oriented batt  12   d  towards top and bottom rollers  34 ,  36 . However, conveyor belt  18  ends prior to reaching the compression system  26 . Accordingly, a gap  38  exists between an end  18   a  of conveyor belt  18  and the start of the compression system  26 . Therefore, when vertically-oriented batt  12   d  enters the compression step E, top and bottom rollers  34 ,  36  may be able to provide compression forces against both top and bottom surfaces of vertically-oriented batt  12   d . The speed of the top and bottom rollers  34 ,  36  may be dependent upon several factors, including, amongst others, the rise times of reaction products in the vertically-oriented batt  12   d  the percent rise of the reaction products in the vertically-oriented batt  12   d  per unit of time, the desired final characteristics of the polymer fill  12 , the speed of the vertically-oriented batt  12   d  coming off of conveyor belt  18 , and the like. It can be appreciated that the invention is not limited to a single set of rollers  32  and may be practiced with any number of sets of rollers  32  so long as the vertically-oriented batt  12   d  may be compressed to the desired thickness.  
         [0023]     Immediately following the compression step E, the compressed vertically-oriented batt  12   e  is deposited onto a wire mesh conveyor belt  42 , such as a Kevlar conveyor belt, and carried to a cooling step F. The cooling step F may be completed by passing the compressed vertically-oriented batt  12   e  through a means for cooling, or cooling system  28 , which may include a duct, an inner chamber  44 , or the like, and an air moving fan  46  connected to inner chamber  44 . As illustrated, fans  46  are located on opposing sides of conveyor belt  42  and at proximately the same height. However, it can be appreciated that the invention may be practiced with fans  46  being placed at any location, including fans  46  placed on the same side of conveyor belt  42 .  
         [0024]     Inner chamber  44  may be located underneath, and extend across the width, of wire mesh conveyor belt  42  and may include a top surface which is open to the ambient air. During operation, fans  46  create a suction force within inner chamber  44 , and as a result, cause the ambient air to be suctioned through compressed vertically-oriented batt  12   e  and into inner chamber  44 . As a result, the ambient air cools the compressed vertically-oriented batt  12   e  as it is suctioned into inner chamber  44 . The wire mesh conveyor belt  42  allows for ambient air to properly flow through compressed vertically-oriented batt  12   e  and into inner chamber  44  when fans  46  are operating. As with the compression step E, the speed of the mesh conveyor belt  42  may be dependent upon several factors, including, amongst others, the setting times of reaction products in the compressed vertically-oriented batt  12   e , the percent rise of the compressed vertically-oriented batt  12   e  per unit of time, the desired final characteristics of the polymer fill  12 , and the like. It should be noted that the cooling system  28  is not limited by the number of inner chambers  44  and fans  46  illustrated, and may be practiced with any number of inner chambers  44  and fans  46 , so long as the compressed vertically-oriented batt  12   e  is properly cooled. Further, it can be appreciated that one fan  46  may be connected to several inner chambers, and vice versa.  
         [0025]     In an alternate embodiment of the invention, cooling system  28  may include an apron  50  placed over the wire mesh conveyor belt  42 , as illustrated in  FIG. 5 . The apron  50  may be supported by jack screws  48 . The jack screws  48  may raise or lower apron  50 , depending upon the distance desired between wire mesh conveyor belt  42  and apron  50 . Apron  50  may include a second means for compressing, such as, for example, a second wire mesh conveyor belt  52 , similar to wire mesh conveyor belt  42 , and a steel roller  54 . When the compressed vertically-oriented batt  12   e  enters the cooling system  28 , steel roller  54  provides additional compression forces on the compressed vertically-oriented batt  12   e . Then, as compressed vertically-oriented batt  12   e  is carried by wire mesh conveyor belt  42  through cooling system  28 , second wire mesh conveyor belt  52  may provide constant, uniform compression forces on compressed vertically-oriented batt  12   e.    
         [0026]     Upon completion of the cooling step F, the polymer fill  12  having a predetermined thickness is formed. It can be appreciated that the polymer fill  12  may be subject to secondary manufacturing processes, such as, for example, a cutting process to cut the polymer fill  12  to any desirable length or shape, or a wrapping process to cover the polymer fill  12  with a decorative cover. Alternatively, the polymer fill  12  may be rolled up and packaged straight from the mesh conveyor belt.  
         [0027]     The embodiments disclosed herein have been discussed for the purpose of familiarizing the reader with novel aspects of the invention. Although preferred embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of the invention as described in the following claims.