Abstract:
A dosing bag filled with dry additive material is made using a dissolvable starch-based film. When the dosing bag with its contents are introduced into a mixture with water, it dissolves and releases its contents. The dosing bags are made in a chain. In this manner, any number of the dosing bags can be removed from the chain for use. The dosing bags are made from film material that is formed into a tube structure. While the tube structure is being partially filled, a section on the interior of the tube structure is shielded from contamination. After the partial filling, the tube is heat sealed closed in the area that was previously shielded. The shielded area is clean of contaminants and enables a high-quality seam to be formed. The shielding, filling, and sealing process is repeated multiple times to create the chain of dosing bags.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/237,916, entitled Dosing Bag Structure For Dispensing Fiber And Admixtures into Cementitious Mixtures, filed Sep. 20, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the structure and manufacture of prepackaged dosing bags that contain dry admixtures and/or fibers that are intended to be added to cementitious mixtures. 
         [0004]    2. Prior Art Description 
         [0005]    Fibers and/or other admixture materials are often added to cementitious products such as concrete. 
         [0006]    Typically, fibers and/or admixture materials are added immediately before or during the mixing of the cementitious product. Fibers and/or admixture materials are used to improve or modify the cementitious material. Fibers and/or other admixture materials are used to modify the properties of concrete in such a way as to improve the product, make the product more suitable for a particular purpose, or for economy. The primary reasons for using fibers and/or other admixture materials in concrete are (1) to achieve certain properties in concrete more effectively than by other means; (2) to maintain a quality of concrete throughout the successive stages of mixing, transporting, placing, and curing; (3) to overcome certain emergencies during concrete making or placing operations; (4) to reduce the cost of concrete construction; and (5) to improve the mixture to control cracking or other detrimental effects. 
         [0007]    In most instances the desired effect within the cementitious material can only be achieved by the use of fibers or admixture materials. In addition, the use of fibers and/or admixture allows for the use of less expensive construction methods or designs and thereby offsets the costs of the add materials. As an example, consider a mixing truck at the end of a delivery that still contains wet concrete within its mixer. If the wet concrete is left in the truck overnight, the residual product will set and begin to harden. While the wet concrete can be washed out of the truck with a large amount of water, the disposal of the liquid may cause an environmental problem. To avoid this problem, it is desirable to delay or retard the setting of concrete so that it remains fluid and can be used the next day. This affect is achieved by adding a retarding admixture to the wet concrete. However, an exact amount of the admixture has to be added. If too much is added, the concrete will not properly cure the next day. If too little is added, the concrete may harden prematurely. 
         [0008]    Fibers and other concrete admixture materials are typically provided as filaments, solids, or powders. As such, they must be mechanically mixed into the concrete in order to be distributed. The more thorough the mixing, the more uniform the fibers and/or admixture materials are dispersed. The successful use of these admixture materials depends upon the accuracy with which they are prepared, the rate of which they are dispensed and the thoroughness of their distribution within the mixture. 
         [0009]    Typically, concrete is made by weighing or volumetrically measuring the ingredients for a batch and introducing all ingredients into a wet mixer. It is important that the amount of fibers and/or admixture material added during batching are carefully controlled. Inaccuracies in the amount of fiber or admixture materials added or the thoroughness of dispersion can significantly affect the properties and performance of the concrete products. The need for accuracy in measuring and having even dispersion of the amount of fibers or admixture materials to be added to a particular batch are particularly acute when a relatively small amount of fibers or admixture materials are required for the product. 
         [0010]    For fibers and/or admixture materials, it is cumbersome and time consuming to accurately weigh the required amount of additives. Thus, workers add fibers and/or admixtures to the concrete in pre-measured and pre-packaged bags. Such bags are known in the industry as dosing bags. The use of pre-measured dosing bags not only minimizes human error in handling and weighing but it also facilitates the process of mixing them into the product. One drawback of using dosing bags is that opening and emptying the pre-packaged dosing bags into the mixer creates a mess, wastes time, and results in some degree of spillage. The spillage contributes to inaccuracies in batching. It also exposes workers to chemicals and dusts that are best not inhaled. 
         [0011]    Another drawback in using prior art dosing bags is that the typical dosing bags is made either from thin paper that is sealed with glue or with a heat seal strip. Workers often just throw these bags into a mix with no concern that the bag and the bag&#39;s seal will not dissolve into the mix. If this debris is not physically removed, it can create flaws in the final concrete product. Furthermore, the additives stuck within the bag tend to get trapped in the bag and clump up. Extra mixing time must therefore be used to ensure that the additives have the opportunity to disperse throughout the mixture. 
         [0012]    Some attempts have been made to develop a dissolving dose bag from dissolvable films such as polyvinyl acetate or polyvinyl alcohol (PVA). Such prior art dosing bags are exemplified by U.S. Pat. No. 4,961,790 to Smith, entitled Concrete Admixture Device and Method Of Using Same. However, such prior art dosing bags are highly sensitive to the humidity in the air. Thus, such prior art dosing bags must be packaged and stored inside an airtight bag or another low-moisture environment. This is highly impractical at most jobsites where concrete is being mixed for use. One humid night can ruin thousands of pounds of additives, if not stored properly at the jobsite. 
         [0013]    Another problem associated with such prepackaged additives, is that the dissolvable packaging disintegrates so rapidly, that the additives held in the packaging never have the opportunity to disperse before they pass into the mixture. Again, the result is that the additives tend to clump together and remain clumped during the mixing process. As a consequence, extra mixing is needed to ensure that the clumps are broken and that the additives have had the opportunity to disperse evenly throughout the mixture. 
         [0014]    A need therefore exists for an improved packaging system for fibers and admixture materials that can be thrown directly into a cementitious mixture, where the package disperses its contents slowly and evenly, yet wherein the packaging completely dissolves. This need is met by the present invention as described and claimed below. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention is a dissolving dosing bag for fiber or other concrete admixtures that is made from a dissolvable starch-based film material. When the dissolving dosing bag with its contents are introduced into a mixture that uses water as an ingredient, and which is agitated for a period of time, the dissolving dosing bag dissolves at a particular rate such that the fiber or other concrete admixtures are released into the mixture in an even manner. 
         [0016]    The dosing bags are made in a chain. In this manner, any number of the dosing bags can be removed from the chain for use. The remaining dosing bags can be retained for later use. The dosing bags are each made from a starch-based film material that can dissolve in water. The film material is formed into a tube structure. Part of the tube structure is filled with fibers or admixture. While the tube structure is being partially filled, a section on the interior of the tube structure is shielded from contamination. This is done either with a fold or with the use of a physical barrier. After the partial filling, the tube is heat sealed closed in the area that was previously shielded. The shielded area is clean of contaminants and enables a high-quality seam to be formed. The shielding, filling, and sealing process is repeated multiple times to create the chain of dosing bags. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    For a better understanding of the present invention, reference is made to the following description of an embodiment thereof, considered in conjunction with the accompanying drawings, in which: 
           [0018]      FIG. 1  is a perspective view of an exemplary embodiment of a chain of dosing bags; 
           [0019]      FIG. 2  is a schematic of a pouch packaging machine that produces the chain of dosing bags shown in  FIG. 1 ; 
           [0020]      FIG. 3  is a cross sectional view of a section of continuous tube structure containing a protective fold; 
           [0021]      FIG. 4  is a cross sectional view of the segment of  FIG. 3  with the fold removed; 
           [0022]      FIG. 5  is a cross sectional view of a section of continuous tube structure protected by a shield; and 
           [0023]      FIG. 6  is a cross sectional view of the segment of  FIG. 3  with the shield retracted. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Although the present invention dosing bag system can be embodied in many ways, the illustrations selected show only a few of the possible embodiments. These embodiments are selected in order to set forth the best modes contemplated for the invention. The illustrated embodiments, however, are merely exemplary and should not be considered a limitation when interpreting the scope of the appended claims. 
         [0025]    Referring to  FIG. 1 , a dosing bag chain  10  is shown. The dosing bag chain  10  is comprised of multiple interconnected dosing bags  12 . Each of the dosing bags  12  is made from a starch-based water dissolvable film  14 . For each of the dosing bags  12 , the dissolvable film  14  is heat sealed around a volume of dry additive material  16 . The dry additive material  16  can be fibers or any other dry or powdered admixture material that a person may want to add to a cementitious mixture. 
         [0026]    The dissolvable film  14  used to make the dosing bag chain  10  is a hydroscopic plastarch material PSM. Several formulations of such PSM materials are commercially available in the marketplace. The composition of a preferred PSM is described in U.S. Patent Application Publication No. 2008/0153958 to Ding, entitled Substantially Completely Biodegradable High Starch Polymer, the disclosure of which is incorporated into this specification by reference. 
         [0027]    The dosing bag chain  10  is made by heat sealing long seams  18  and lateral seams  20  between and around deposits of the dry additive material  16 . This creates sealed pockets  22  within each dosing bag  12  that isolate the dry additive material  16 . The pockets  22  defined by each dosing bag  12  preferably hold less than 0.5 pounds of additive material  16  and may be so small that they hold only one or two ounces. During manufacturing, the dosing bags  12  are interconnected into large dosing bag chains  10 . The dosing bags chains  10  are then packaged in larger boxes, such as a five pound box or a twenty pound box. 
         [0028]    For example, suppose that a particular batch of cementitious material requires 16¾ pounds of reinforcement fibers for a particular application. Using the present invention system, the fibers can be prepackaged in ¼ pound dosing bags  12 . Eighty such dosing bags  12  can then be packaged into a twenty pound box. To meet the requirement, a worker needs to open the box and toss sixty seven dosing bags  12  into the mix in order to precisely meet the 16¾ pound requirement without waste. The remaining thirteen remaining dosing bags  12  are saved for later use. Since the dosing bags  12  are tossed whole into a mixer, there is no labor wasted in measuring and dumping the fibers. Furthermore, since the dosing bags  12  are never opened by the worker, there is no danger of chemical contamination or inhalation hazards from the additive material  16 . 
         [0029]    The addition of multiple small dosing bags  12  into a mixer, rather than the addition of a few large bags greatly increases the thoroughness at which the additive material  16  is dispersed throughout the mixture. As a result, the likelihood that additive material  16  clumping will occur is greatly reduced. 
         [0030]    The dissolvable film  14  is heat sealed along the long seams  18  and lateral seams  20  that define the edges of each of the dosing bags  12  in a dosing bag chain  10 . However, the dosing bags  12  are often filled with fine fibers or with fine powders. As the dosing bags  12  of dissolvable film  14  are filled, static often causes the fine powders to adhere to the dissolvable film  14 . As a result, the dissolvable film  14  becomes contaminated. This contamination on the dissolvable film  14  can prevent the dissolvable film  14  from properly being heat sealed along a lateral seams  20 . As a result, the lateral seam  20  between the dosing bags  12  can leak after the heat bonding process. 
         [0031]    Referring to  FIG. 2  in conjunction with  FIG. 1 , a method of manufacturing the dosing bag chain  10  is described that eliminates the problem of film contamination and ensures proper heat sealed seams. In  FIG. 2 , a vertical pouch packaging machine  25  is provided. Two rolls  26 ,  27  of dissolvable film  14  are provided. Both rolls  26 ,  27  pass through vertical seamer  28  that join the dissolvable film  14  together along common long seams  18 . This creates a continuous tube structure  30  from the dissolvable film  14 . It will be understood that a continuous tube structure  30  can be made from a single roll of dissolvable film  14 , provided the film is shaped into a cylinder and sealed along the one long seam. Regardless, a continuous tube structure  30  of dissolvable film  14  is presented. 
         [0032]    PSM film materials have a tendency to generate static charges as they are pulled off the rolls  26 ,  27  and travel through the guides of the vertical pouch packaging machine  25 . Consequently, any fine particulate matter floating in the air near the dissolvable film  14  has a tendency to cling to the dissolvable film  14 . The bottom of the continuous tube structure  30  is initially heat sealed closed. This initial bottom lateral seal can be made in a contaminant free environment. However, subsequent lateral seals  20  must be made in an environment that is polluted with the dry additive material  16  being used to fill the dosing bags  12 . 
         [0033]    The vertical pouch packaging machine  25  has a fill chamber  32 . In the fill chamber  32 , a predetermined volume of dry additive material  16  is released into the continuous tube structure  30 . The dry additive material  16  passes into the continuous tube structure  30  through a fill conduit  34 . 
         [0034]    Prior to the dry additive material  16  being released, the continuous tube structure  30  passes through a folding mechanism  36 . Referring to  FIG. 3 , it can be seen that when the continuous tube structure  30  passes into the folding mechanism  36 , the folding mechanism  36  creates a short invaginated fold  40  in the dissolvable film  14 . The fold  40  is essentially S-shaped. After the fold  40  is created, a volume of dry additive material  16  is deposited into the continuous tube structure  30 . Referring to  FIG. 4  in conjunction with  FIG. 3 , it will be understood that as the dry additive material is deposited, the exposed interior surfaces  42  of the tubular structure become contaminated with dust from the dry additive material  16 . The presence of the contamination would prevent the dissolvable film  14  from being sealed together properly above the dry additive material  16 . 
         [0035]    Referring to  FIG. 4  in conjunction with  FIG. 3 , it can be seen that after the dry additive material  16  is deposited, the fold  40  in the continuous tube structure  30  is undone. This creates a clean zone  44  on the interior of the continuous tube structure  30  that is not contaminated by the dry additive material  16 . Returning to  FIG. 2 , it can be seen that continuous tube structure  30  then passes into a lateral heat sealer  46  that creates the lateral seals  20  the continuous tube structure  30 , therein creating a dosing bag  12 . The lateral heat sealer  46  can be many commercial plastic sealing machines. A preferred machine is the Model PSF-400 impulse heat sealing machine made by the Cleveland Equipment &amp; Machinery Company of Memphis, Tenn. The lateral seam  20  is made across the clean zone  44 . As such, the lateral seam  20  is made free from contamination. The result is a high quality lateral seal  20  that is consistent between each of the dosing bags  12  in the dosing bag chain  10 . 
         [0036]    Each lateral seam  20  is made wide enough to serve as the top seal of one dosing bag and the bottom seal of the next subsequent dosing bag. Each lateral seam  20  then passes through a perforator  48 , which perforates the lateral seam  20  so that the dosing bags  12  can be readily separated without disrupting the integrity of the dosing bags  12 . 
         [0037]    The fold  40  formed in the dissolvable film  14  is only one way to protect a section of the dissolvable film  14  from contamination. Another method is to use a shield barrier during the fill process. Referring to  FIG. 5  and  FIG. 6 , it can be seen that a protective barrier  50  can be mechanically applied to the interior surface  42  of the continuous tube structure  30  as the dry adhesive material  16  is being deposited. After the dry adhesive material  16  is deposited, the protective barrier  50  retracts. This leaves a clear zone  52 . The clear zone  52  can then pass into the lateral heat sealer  46 , where the clear zone  52  is set into a lateral seam  20 . 
         [0038]    It will be understood from  FIG. 2  that pouch packaging machine  25  creates the chain  10  of dosing bags  12 . The dosing bags  12  each have the same volume of admixture material. However, the volume can be preselected on the pouch packaging machine  25 . Provided the dosing bags  12  are kept dry, each of the dosing bags  12  in the chain  10  remains intact and the contents of each dosing bag  12  are confined. The dosing bags  12  are separated from the chain  10  to be added to a mixer  55 . However, all the dosing bags  12  are not added simultaneously. Rather, the dosing bags  12  are added to a mixer one or a few at a time so that the dry additive material  16  are released over a prolonged period of time. This relative slow release of the dry additive material  16  is occurring during the mixing of the cementitious material. As a result, the admixture materials  14  are provided with the opportunity to be thoroughly dispersed throughout the cementitious mixture without any clumping. 
         [0039]    Due to the dissolvability of the dosing bags  12 , the dosing bags  12  will continuously release their contents over a span of about thirty seconds to ninety seconds. At the end that period of time, the dosing bags  12  dissolves to a point where they lose all structural integrity and all of their contents are released. 
         [0040]    In the mixer  55 , there are moving agitators and mixing occurs fairly rapidly. A dosing bag  12  that releases material in a sixty-second timeframe enables the material being dispensed to fully intermix throughout the cementitious mixture. Furthermore, since each dosing bag  12  releases its contents over this prolonged period of time, there are no clumps or balls of material that can pass through the mixer  55  without being properly integrated. 
         [0041]    It can be seen from the foregoing discussion that the present invention solves most of the problems encountered in the prior art practice. It is believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method and device shown and described have 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 claims.