An environmentally friendly vegetation growth-enhancing erosion control blanket is formed from an elongated rectangular excelsior/wood wool mat. The mat is held together with threads stitched therein. When the finished blanket is placed atop the ground, the blanket serves to shield the earth area from wind and water erosion forces, without the presence of the plastic netting often used in the prior art. As the ground vegetation grows, it ultimately replaces the blanket which decomposes and furnishes the ground vegetation with a nutritive mulch.

CROSS-REFERENCE TO OTHER APPLICATION(S)  
       [0001]     This application claims priority to and incorporates by reference the entirety of U.S. Provisional Application Ser. No. 60/532,843 filed Dec. 23, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to erosion control blankets for inhibiting ground erosion in flat or sloping, often bare earth areas, or channels, where water flows, and, more particularly, but not by way of limitation, to fibrous erosion control blankets adapted to permit ground vegetation to grow upwardly therethrough and manufactured without conventional netting.  
         [0004]     2. History of the Prior Art  
         [0005]     For both aesthetic and environmental protection reasons, it is often necessary or desirable to grow ground vegetation, such as grass, on flat land or slopes, channels, and bare earth areas to inhibit erosion due to the effects of wind and rain. The successful sprouting and growth of ground vegetation planted on these areas, however, is often prevented by the soil erosion which the planted vegetation is designed to inhibit, the erosion frequently carrying away at least some portion of the soil before it the vegetation takes hold.  
         [0006]     To alleviate this problem, it is now a common practice to cover the area with fibrous, mat-like members commonly referred to as erosion control blankets. One particularly effective erosion control blanket is the Curlex® or excelsior blanket manufactured and sold by the American Excelsior Company of Arlington, Tex. since 1964. This erosion control blanket is fabricated, in elongated rectangular mat form, from elongated, randomly intertwined fiber commonly referred to as “excelsior” or “wood wool.” The fiber mats have historically been held together or contained by photodegradable or netting material, which form nets on one or both sides of the fiber. The blanket-net assemblies are then conveniently packaged in individually rolled bundles to facilitate their handling and transport to the erosion control job site. The netting is generally necessary during manufacturing, shipping and the subsequent job site installation in order to maintain the integrity of a fibrous mat.  
         [0007]     At the job site, the blanket bundles are unrolled in a side-to-side relationship along the earth area to be protected against erosion, and are secured along the sides of one another and to the underlying ground area with the use of a spaced series of conventional ground staple members, which may be made of steel, wood, plastic or starch. The installed blankets generally have parallel sides and abut one another to form a substantially solid surface to shield the underlying earth area, and thus the planted ground vegetation therein, from wind and water erosion forces.  
         [0008]     The individual fibers forming the mat portions of various types of the blankets collectively define therebetween a multiplicity of small interstitial regions through which the planted ground vegetation may upwardly sprout and grow. During such shielded vegetation growth, some varieties of the blankets, such as the Curlex® blanket decompose, ultimately being replaced by the emerging ground vegetation.  
         [0009]     Despite the erosion control effectiveness of these excelsior/wood wool blanket-net assemblies, and similar blankets formed from other fibrous-net materials, erosion control blankets of this general type have a distinct disadvantage. The problem pertains to the use of the netting material often utilized to contain the fiber. Although the netting may be photodegradable, it may last long enough to present ecological and maintenance problems. It has been reported that conventional netting is capable of trapping birds and other small wildlife attempting to nest or inhabit the erosion control blankets. Until the netting material photodegrades, it does present an ecological impediment to normal animal activity. In addition, the netting, which often forms a large grid of material that can become entangled in mowing equipment before the material photodegrades.  
         [0010]     In U.S. Pat. No. 5,735,982, herein incorporated by reference in its entirety, a net free erosion control blanket is described. As described therein, the erosion control blanket is held together by a bonding agent such as latex. Although, the above-described blanket does not include a net and therefore provides the advantages of a net-free assembly, the use of latex is, in some instances, cost prohibitive. In those instances where the entire erosion control blanket must biologically degrade as does excelsior/wood wool, a different system of securement for the excelsior/wood wool fibers is necessary. The present invention provides such a system by incorporating a stitching technique, which in conjunction with the intertwined relationship of the excelsior/wood wool fibers, as described herein, provides an effective erosion control blanket that is environmentally friendly.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention relates to erosion control blankets. More particularly, one aspect of the invention relates to a vegetation growth-enhancing erosion control blanket having a first surface that may be placed upon, and in contact with, an area on which ground vegetation is to be grown, and a second surface opposite thereto. The blanket includes a flexible mat of intertwined, elongated members, the members collectively defining in the mat a multiplicity of interstitial regions through which portions of the growing ground vegetation may pass generally transversely to said mat. At least a major portion of the members are held in place with a thread stitched therethrough in a manner providing the mat with structural integrity. The second surface of the mat includes a combination of the thread and the members for subsequent physical degradation following the erosion control. In one embodiment, the thread is generally biodegradable.  
         [0012]     In another aspect, the present invention relates to a method of manufacturing an erosion control blanket. The method includes the steps of forming a flexible mat of intertwined, elongated members, said members collectively defining a multiplicity of interstitial regions in said mat through which vegetation may pass, and securing at least a major portion of said members via stitching a thread through a top surface and a bottom surface of the mat. In one embodiment, the thread is generally biodegradable.  
         [0013]     In another aspect, one embodiment of the invention includes a vegetation growth-enhancing erosion control blanket having a first surface that may be placed upon, and in contact with, an area on which ground vegetation is to be grown, and a second surface opposite thereto. The blanket comprises a flexible mat of intertwined, elongated members, the members collectively defining in the mat a multiplicity of interstitial regions through which portions of the growing ground vegetation may pass generally transversely to the mat. At least a major portion of the members are held in place with a thread stitched therethrough in a manner providing the mat with structural integrity. The second surface comprises the top of the mat affording a combination of the thread and the members for subsequent physical degradation following the erosion control. In one embodiment, the thread is generally biodegradable and may be comprised of rayon, cotton, jute, or the like. In another embodiment, the elongated members comprise Curlex® excelsior/wood wool.  
         [0014]     In yet a further aspect, one embodiment of the invention comprises a method of manufacturing an erosion control blanket. The method includes the steps of forming a flexible mat of intertwined, elongated members, the members collectively defining a multiplicity of interstitial regions in the mat through which vegetation may pass. At least a major portion of the members are secured through stitching a thread through a top surface and a bottom surface of the mat. In another embodiment, the thread is generally biodegradable and may be comprised of rayon, cotton, jute or the like. In yet another embodiment the above described method further includes the step of passing the stitched mat under thread tensioning rollers. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:  
         [0016]      FIG. 1  is a fragmentary perspective view of a sloping ground area covered by a series of vegetation growth-enhancing erosion control blankets;  
         [0017]      FIG. 2  is an enlarged, fragmentary perspective view of a portion of an erosion control blanket;  
         [0018]      FIG. 3  is an enlarged top plan view of one embodiment of an erosion control blanket constructed in accordance with the principles of the present invention;  
         [0019]      FIG. 4  is a side elevational view of the erosion control blanket of  FIG. 3 ;  
         [0020]      FIG. 5  is a diagrammatic top view of an erosion control blanket manufacturing process in accordance with one embodiment of the principles of the present invention;  
         [0021]      FIG. 6  is a diagrammatic side view of the erosion control blanket manufacturing process of  FIG. 5 ;  
         [0022]      FIG. 7  is an enlarged view of a stitching portion of the erosion control blanket manufacturing process of  FIG. 5 ; and  
         [0023]      FIG. 8  is an enlarged view of the stitching portion of the erosion control blanket manufacturing process of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Referring first to  FIG. 1  there is shown in simplified form a section of ground having a downwardly sloping earth portion  12  normally subject to undesirable wind and water erosion forces, and upon which erosion-inhibiting ground vegetation is to be grown. Covering the sloping earth portion  12  are a series of specially designed vegetation growth-enhancing, erosion control blankets  114 . Blankets  114  have a porous construction through which the planned-for ground vegetation may readily germinate and grow.  
         [0025]     Referring still to  FIG. 1 , the blankets  114  have elongated, generally rectangular configurations (zig-zag shaped sides  115 , in this embodiment) and are conventionally secured to one another and to the underlying sloping earth portion  12 , by a spaced series of ground staples  16 . Installed in this manner, the blankets  114  shield the sloping earth portion  12  from both wind and rain until the ground vegetation takes hold.  
         [0026]     Referring still to  FIG. 1 , each of the erosion control blankets  114  includes an elongated rectangular mat  118  formed from fibrous material—i.e., a multiplicity of elongated fibers  20  disposed in a randomly intertwined relationship. Wood fibers  20  of the excelsior/wood wool variety are preferably used and collectively define therebetween a multiplicity of relatively small interstitial regions through which ground vegetation, such as the grass  22  may upwardly grow from the sloping earth portion  12  protectively covered by blankets  114 . Each mat  118 , in this particular embodiment, has a substantially flat bottom surface  124 , positionable directly against the sloping earth portion  12 , a portion of which being diagrammatically illustrated, as will be described in more detail below.  
         [0027]     Referring now to  FIG. 2 , an enlarged, perspective view of a portion of a prior art erosion control blanket  114  is shown. Some prior art blankets  114  are formed with straight sides  115  and at least one layer of a photodegradable netting  128  extending across a top side  126  to form a mat  118 . A second plastic net  130  may be attached to the bottom side of the blanket to extend generally parallel to the top net member  128 . Netting  128  and  130  serve to flexibly reinforce conventional mats  118  and facilitate their handling during installation of the erosion control blankets  114 .  
         [0028]     From a structural standpoint, the prior art erosion control blankets  114  are effective for erosion control. One embodiment of the blanket  114  shown in  FIG. 2  has been manufactured and sold by the American Excelsior Company, Arlington, Tex. under the trade name “Curlex.” However, in accordance with an important aspect of one embodiment of the present invention, the nettings  128  and  130 , which may create ecological problems, have been removed and replaced with a thread binding as described below.  
         [0029]     Referring now to  FIG. 3  there is shown an enlarged top plan view of an erosion control blanket  14  illustrating one aspect of the fabrication thereof in accordance with one embodiment of the principles of the present invention. The top surface  26  of erosion control blanket  14  is bound in place by thread  30 . In one embodiment, the thread  30  may be generally biodegradable and made of rayon, cotton, jute or the like. The thread  30  is held in place by stitches  32  that perforate through the top surface  26  of the blanket  14  to the bottom surface  34  of the blanket  14 . In the preferred embodiment, the threads are similarly spaced horizontal threads  30  bound in place by stitches  32  at regular intervals along the blanket  14 . However, other orientations of threads  30  and stitches  32  may be utilized in accordance with aspects of the present invention. For example, vertical or diagonal threads  30  may be implemented and held in place by randomly positioned stitches  32 .  
         [0030]     Referring still to  FIG. 3 , the fibers  20  of this particular embodiment are packaged in an intertwined manner and held together with thread  30  and stitches  32  as described above. The fibers  20 , in the preferred embodiment, are wood material shaved to form Curlex® excelsior fibers  20  with barbed edges. 80% of the fibers  20  are six inches or longer with a consistent width and thickness. The barbed edges and curled orientation of the fibers  20  interlock and assist in holding the blanket  14  together. It should be noted, however, that the fibers  20  of the present invention may include any elongated members of wood wool which may be intertwined into a flexible mat. Curlex® excelsior fibers comprise the preferred embodiment but other wood wool is contemplated by the present invention.  
         [0031]     Referring now to  FIG. 4  there is shown a side elevational view of the blanket  14  of  FIG. 3 . Consistent therewith, the stitches  32  are shown as vertical lines extending from the top surface  26  to the bottom surface  34  substantially near the threads  30 . As previously mentioned, the stitching pattern and threads  30  may be in a variety of orientations other than the preferred embodiment shown. The bottom surface  34  is substantially flat and engages the surface of the sloping earth portion  12  as shown in  FIG. 1  to permit the infiltration of soil thereagainst and the stabilization of the blanket  14  thereupon.  
         [0032]     Referring now to  FIGS. 5 and 6  there is shown a method of manufacturing the control blanket  14  of the present invention. The manufacturing process occurs by accumulating fibrous material  204 , preferably of the excelsior/wood wool variety, placing it within a hopper  206  where it is compacted and discharged from the hopper end  208 . The discharged mat  210  is received upon a conveyor belt  209  which transports the mat  210  to a stitching area. A roller  212  is positioned adjacent a stitcher head  214  to further compress the mat  210  prior to stitching. The stitching head  214  is described with greater detail below with reference to  FIG. 6 . The threads  30  are stitched into place and the stitched blanket  14  is later packaged for distribution.  
         [0033]     Referring now to  FIGS. 7 and 8 , the stitcher head and stitching of the mat  210  are shown in greater detail. Stitches  32  are placed through the top surface of the mat  210  at the stitcher head  214  and the blanket  14  formed is then passed under thread tensioning rollers  216  to maintain the proper tension of the thread  30 . The thread  30  runs from an upper area of the machine toward a stitching needle  218 . The stitching needle  218  pulls the thread  30  through the top surface of the mat  210  to the bottom surface of the mat  210 . The stitching needle  218  then returns past the top surface of the mat  210  to prepare for another stitch. The stitching needle  218  engages the mat at appropriate intervals as discussed above. After the mat is stitched, the blanket  14  is compressed and the thread tensioning rollers  216  maintain proper tension of the thread  30 . A pressure adjusting bolt  220  may be utilized to adjust the tension of the rollers  216 . The formed blanket  14  may then be rolled or cut at specific intervals and packaged for distribution.  
         [0034]     The above-referenced stitching system is useful in the manufacture of an erosion control blanket due to the multiplicity of elongated, intertwined members that collectively define a multiplicity of interstitial regions with which the stitching is permitted to secure the intertwined members together. It has been noted that the propensity of excelsior/wood wool to maintain the intertwined relationship lends itself to the stitching technique defined herein, and provides an erosion control blanket for multiple environmentally-safe applications where other fibrous type materials may not lend themselves to such a stitching operation. As referenced above, a generally biodegradable thread is a preferred embodiment. However, one embodiment includes a thread made of polypropylene or the like. The length of thread in the biodegradable excelsior mat of the present invention presents a more environmentally friendly configuration than prior art “net” mats.  
         [0035]     It is thus believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method and apparatus shown or described has been characterized as being preferred it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the following claims.