System and Method for Producing Dosing Bags that Are Filled with Dry Additives for Use in Cementitious Mixtures

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

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

1. Field of the Invention

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.

2. Prior Art Description

Fibers and/or other admixture materials are often added to cementitious products such as concrete.

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.

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.

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.

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.

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.

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'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.

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.

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.

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

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.

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

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:

FIG. 1 is a perspective view of an exemplary embodiment of a chain of dosing bags;

FIG. 2 is a schematic of a pouch packaging machine that produces the chain of dosing bags shown in FIG. 1;

FIG. 3 is a cross sectional view of a section of continuous tube structure containing a protective fold;

FIG. 4 is a cross sectional view of the segment of FIG. 3 with the fold removed;

FIG. 5 is a cross sectional view of a section of continuous tube structure protected by a shield; and

FIG. 6 is a cross sectional view of the segment of FIG. 3 with the shield retracted.

DETAILED DESCRIPTION OF THE INVENTION

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 & 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.

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.

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.

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.

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.

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.

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.

Claims

1. A method of manufacturing a dosing bag containing dry additive material for use in a cementitious mixture, said method comprising the steps of:

providing a film of material that can dissolve in water;

forming said film into a tube structure, wherein said tube structure has an interior surface;

filling part of said tube structure with said dry additive material;

shielding a clean section of said interior surface during said step of filling to prevent said clean section from becoming contaminated with said dry additive material; and

heat sealing said tube structure closed in said clean section to create a lateral seam.

2. The method according to claim 1, further including the step of perforating said lateral seam.

3. The method according to claim 1, wherein said film has two long edges and wherein said step of forming said film into a tube structure, further includes heat sealing said two long edges together into a long seam.

4. The method according to claim 1, wherein said film is supplied on two separate rolls and said step of forming said film into a tube structure further includes heat sealing said film from said two separate rolls together along long seams.

5. The method according to claim 1, wherein said step of shielding a clean section of said interior surface includes creating an invaginated fold in said tube structure prior to said step of filling.

6. The method according to claim 1, wherein said step of shielding a clean section of said interior surface includes placing a barrier over said clean section prior to said step of filling.

7. A method of manufacturing a chain of dosing bags, wherein each of said dosing bags in said chain contains a volume of dry additive material, said method comprising the steps of:

i. providing a film of material that can dissolve in water;

ii. forming said film into a tube structure, wherein said tube structure has an interior surface;

iii. shielding a clean section on said interior surface;

iv. filling part of said tube structure with said dry additive material;

v. heat sealing said tube structure closed in said clean section to create a lateral seam and form an dosing bag having said dry additive material isolated therein; and

repeating steps ii, iv and v to create said chain of dosing bags.

8. The method according to claim 7, further including the step of perforating said chain between each of said dosing bags.

9. The method according to claim 7, wherein said film has two long edges and wherein said step of forming said film into a tube structure, further includes heat sealing said two long edges together into a long seam.

10. The method according to claim 7, wherein said film is supplied on two separate rolls and said step of forming said film into a tube structure further includes heat sealing said film from said two separate roles together along long seams.

11. The method according to claim 7, wherein said step of shielding a clean section of said interior surface includes creating an invaginated fold in said tube structure.

12. The method according to claim 7, wherein said step of shielding a clean section of said interior surface includes placing a barrier over said clean section during said step of filling.

13. A method of introducing a required weight of additives to a cementitious mixture in a mixer, said method comprising the steps of:

creating a chain of interconnected dosing bags joined together along perforated seams that enable each of said dosing bags to be selective separated from said chain, wherein each of said dosing bags is filled with a unit weight of said additives that is a whole number derivative of said required weight, and wherein each of said dosing bags is formed from film that is dissolvable in water;

separating a plurality of said dosing bags from said chain, wherein said second weight of said additives in said dosing bags separated from said chain add up to equal said required weight;

adding dosing bags separated from said chain into said mixer with said cementitious material, wherein each of said dosing bags separately dissolves and releases said additives, and wherein said mixer distributes said additives throughout said cementitious material.

14. The method according to claim 13, wherein said step of creating a chain of interconnected dosing bags includes the sub-steps of:

forming said film into a tube structure, wherein said tube structure has an interior surface;

heat sealing lateral seams in said tubular structure to form interconnected bags; and

filling said bags with said dry additive material to form said dosing bags.

15. The method according to claim 14, further including the substeps of:

shielding clean sections on said interior surface;

heat sealing said tube structure closed in said clean sections to create said lateral seams.

16. The method according to claim 13, wherein said step of creating a chain of interconnected dosing bags includes forming dosing bags that each hold between one ounce and one pound of said additives.

17. The method according to claim 13, wherein said step of creating chain of interconnected dosing bags includes creating dosing bags with heat sealed seams.