Patent Application
20140178592
The subject matter disclosed herein relates generally to non-woven matrices and, more particularly, to cotton shoddy and/or natural fiber matrices and systems and methods for producing cotton shoddy matrices.
Commercially available technology exists today for the purpose of applying liquids to a non-woven matrix, such as a matrix constructed from natural fiber and/or cotton shoddy. One technology includes dipping a continuous feed of a non-woven matrix into a tank of emulsion resin, then squeezing the resin-saturated matrix to remove excess content, while a second technology includes converting emulsion resin into a dense foam using a foam generating system, and injecting the foam into the matrix under pressure using a specially designed application head made for this purpose. While both of these technologies may work to some degree for certain natural fiber non-woven matrices, neither is well suited to resin-saturate cotton shoddy.
Several disadvantages exist with conventional foam injection processes. Foam injection requires a continuous feed of a non-woven matrix. After foam is injected into the non-woven matrix, the non-woven matrix is cut to appropriate size requirements and dried prior to final processing. Further, foam injection requires a wider matrix than an actual foam application area. This excess material provides an edge seal to prevent foam from escaping from an edge area of the continuously moving matrix during foam impregnation. This process does not allow the recycling of the excess of material after cutting to size before resin impregnation. In addition, only one side of the continuously feed matrix can be injected with foam having a certain desired uniformity of application. This, therefore, requires two passes of the non-woven matrix through the foam injection applicator in order to completely resonate the non-woven matrix. Foam injection also tends to be expensive. Capital costs are higher, process application of resonating matrix is slower, and therefore this is an undesirable means of applying a liquid resin into non-woven matrix.
Several disadvantages also exist with conventional dip and squeeze processes. The conventional dip and squeeze process is often undesirable because of problems associated with accuracy of application. However, dip and squeeze may have a better throughput capability than conventional foam injection processes. Similar to the foam injection process, conventional dip and squeeze technology requires the product to be run using a continuous feed of non-woven matrix. It does not allow the recycling of the excess material after cutting to size before resin impregnation.
It is desirable to develop an application system that utilizes the simplicity of a dip and squeeze process or applying the resin on a scrim and then laminating the scrim on a matrix made of thermoplastic and cotton shoddy and/or natural fibers, and achieves the accuracy results of a foam injection process, while doing so with a feed of precut matrix blanks as opposed to roll goods required for existing technology.
In one aspect, a process system incorporates a modified dip and squeeze process system combined with a modified injection system that pumps non-foam resin directly into a non-woven matrix while the non-woven matrix remains substantially submerged in a resin contained within a resin tank.
In another aspect, a method for producing cotton shoddy and/or natural fiber matrices includes a modified dip and squeeze process combined with a modified injection process that pumps non-foam resin directly into the non-woven matrix while the non-woven matrix remains substantially submerged in a resin contained within a resin tank.
The embodiments described herein are directed to a non-woven matrix, such as a non-phenol formaldehyde cotton shoddy matrix, for example, and a process system for the application of a suitable emulsify resin, such as an Acrodur™ resin available from BASF Aktiengesellschaft Corp., Ludwigshafen am Rhein, Germany, for example, that substantially completely saturates the cotton shoddy matrix through a thickness of the cotton shoddy matrix. In certain embodiments, the process system is scalable to meet any application requirement. In addition and for means of practicality, in certain embodiments the system design intent includes the ability to resonate individual cut sheet sizes without the need for a continuous feed of matrix. This will facilitate recycling the excess of material after cutting to size before resin impregnation.
In the following description, the embodiments are described in relation to a cotton shoddy matrix. This is by way of example only, it being understood that the embodiments may be implemented for use with suitable natural fiber non-woven matrices.
In one embodiment, the process system incorporates a modified dip and squeeze process system combined with a modified injection system that pumps non-foam resin directly into the non-woven matrix while the non-woven matrix remains substantially submerged in a resin contained within a resin tank, as described in greater detail below with reference to
Resonating cotton shoddy with a liquid resin product is virtually impossible to achieve using existing dip and squeeze technology. A cotton shoddy non-woven matrix does not have sufficient tensile strength to carry the matrix through a conventional dip and squeeze system without tearing under the nominal tensile pulls that are typically exerted on a product during a resin application and post-matrix drying. Additionally, the wet pick up rate (the rate of added weight of resin and water to fully impregnate the cotton shoddy matrix) adds more than 110% additional weight to a pre-resonated matrix weight. The additional weight, in addition to the weak strengths of short fiber cotton shoddy, renders existing technologies impractical to adopt for this purpose.
Referring to
In one embodiment, upper carrying belt 32 is a fiberglass-reinforced, Teflon™ coated open webbing belt, as described above with reference to lower carrying belt 22, although other belts can be used as upper carrying belt 32. In other embodiments, upper carrying belt 32 may be the same as or different than lower carrying belt 22. Upper carrying belt 32 is operatively coupled to and supported by stainless steel frame 24, one or more belt rolls 36, and an adjustable compression roll 38. A belt drive unit 40 is configured to drive upper carrying belt 32 about belt rolls 36. In one embodiment, belt drive unit 40 includes a PLC-controlled, AC inverter drive with gear reductions for upper carrying belt 32. Alternatively, belt drive unit 30 may include a PLC-controlled, AC inverter drive with gear reductions for upper carrying belt 32, as well as for lower carrying belt 22.
Referring again to
In one embodiment, electrically-driven screw jacks 44, shown in
Referring to
Alternatively, referring to
Process system 10 as described with reference to drying station 14 shown in
Referring again to
Lower carrying belt 22 and upper carrying belt 32 meet to secure or trap the precut matrix blank 43 between lower carrying belt 22 and upper carrying belt 32 prior to or as matrix blank 43 enters tank 20 containing a liquid resin, such as an aqueous solution of a resin and water. As lower carrying belt 22 and upper carrying belt 32 move through tank 20, matrix blank 43 secured between opposing and cooperating lower carrying belt 22 and upper carrying belt 32 is submerged into the aqueous solution contained within tank 20 at a suitable speed to ensure that matrix blank 43 is submerged in the aqueous solution for a sufficient exposure time so that full saturation of the resin throughout matrix blank 43 is achieved. For highly absorbent and dense products, such as cotton shoddy, lower carrying belt 22 and upper carrying belt 32 slide between two stainless steel spring loaded plates that cover a full width of the belts and at least 24 inches of a running length of the belts at any time. One or more nozzles are positioned in a middle portion of each plate in a machine direction, and run across the width of the each plate. Resin is pumped through the one or more nozzles at a predetermined velocity to force resin into a center of matrix blank 43 while matrix blank 43 moves in the machine direction. An added length of the plates ensures that pressure is focused in a desired treatment area. Pre-load spring pressure is sufficient to keep the nozzles and pressure plates compressed to each belt, thereby forming a seal to prevent resin blow by. Resin is forced under pressure into matrix blank 43 to facilitate accelerating absorption of the resin to a center core of matrix blank 43. Other matrices can be resonated similarly to accelerate the resonating speed, but this is the only process which ensures cotton shoddy is fully resonated throughout a Z dimension.
At the end of the submersion process, lower carrying belt 22 and upper carrying belt 32 carrying the resin impregnated non-woven matrix blank 43 tum 90 degrees upwards ascending above tank 20 and entering a squeeze process to remove excess liquid resin to achieve the desired application rate. Using cooperating fixed compression roll 28 and adjustable compression roll 38, with lower carrying belt 22 and upper carrying belt 32 securing matrix blank 43 therebetween, matrix blank 43 moves into and through the squeeze rolls. In one embodiment, three compression roll sets are used, one above the other, to facilitate extracting excess resin from the resonated matrix blank. Each of the three vertical compression rolls, as shown in
Example of formulation for application of liquid resin is as follows.
Wet pick up for cotton shoddy to fully wet out matrix blank during solution application is greater than 125% or 1250 gsm of aqueous solution, pick up during dipping matrix in solution or 55%′ greater dilution in solution mix in order to apply 230 gsm dry solids resin. Therefore the aqueous solution mix needs to be further diluted to (100/18)=5.55×230=1276 gsm.
After resin impregnation, the impregnated matrix blank 43 is dried of excess water prior to use. Because the rate of water evaporation is very high compared to the final matrix blank weight (up to 70%), conventional technology using air impingement driers to perform this task requires ovens lengths often exceeding 50 feet and normally greater than 100 feet in length to run at any appreciable speed. This large foot print takes up valuable floor space and, as a means of energy utilization for drying, is one of the least efficient means to control drying costs. Based on test results, adopting microwave technology in the processing line reduces operating costs and reduces floor space requirements. Microwave oven technology works on the principal of exciting water molecules through energy waves causing the water molecules to vibrate rapidly. Further, microwave technology works on the mass inside out, a more desirable drying method than conventional air impingement ovens that work through transpiration or wicking water from the inside to the drier outside. Because final moisture content is critical to thermal processing (Acrodur™ resin requires moisture to be present in a sufficient quantity to cross-link resin), microwave heating and the ability to precisely control the amount of applied energy allows the process system to deliver matrix blank 43 having a desired pre-set moisture content exiting the drying oven without overheating matrix blank 43. Also, due to the intense focused energy microwave technology offers, the footprint required for oven drying is reduced by 75% over conventional hot air impingement-type drying. Therefore, in contrast to a conventional air oven that must be about 100 feet long to dry matrix blanks, a microwave drying oven, such as described herein, may be less than 25 feet in length. With the use of focused energy, the amount of energy required to dry the same material in the same time cycle is also greatly reduced.
In certain embodiments, cotton shoddy was formulated to include, without limitation, the following: cotton shoddy comprising cotton shoddy ranging from 10% to 90% of dry composite matrix weight, and hi-component polyester fiber ranging from 10% to 90% of composite matrix weight, and natural fiber comprising one or more of the following: jute, tossa, hemp, cori, sisal, curaua, kenaf and other similar fibers ranging from 5% to 90% of composite matrix weight, and polyester fiber ranging from 10% to 90% of matrix weight.
An exemplary Composite Matrix Weight 770 gsm, comprises the following:
10% hi-component polyester=(770×0.10)=77 grams. 1.
35% natural fiber of any fiber type above=(770×0.35)=269.5 grams. 2
55% cotton shoddy=(770×0.55)=432.5 grams. 3
Another exemplary Composite Matrix has the same weight as follows:
10% bi-component polyester=(770×0.10)=77 grams. 1
90% cotton shoddy=(770×0.90)=693 grams. 2
Yet another exemplary Composite Matrix has the same weight as follows:
10% hi-component polyester=(770×0.10)=77 grams. 1
35% polyester fiber of any fiber type above=(770×0.35)=269.5 grams. 2
55% cotton shoddy=(770×0.55)=432.5 grams. 3
Yet another exemplary Composite Matrix has the same weight as follows:
10% bi-component polyester=(770×0.10)=77 grams. 1
20% polyester fiber of any fiber type above=(770×0.20)=154 grams. 2
45% cotton shoddy=(770×0.45)=346.5 grams. 3
25% natural fiber of any fiber type above=(770×0.25)=192.5 grams. 4
The combination of fiber types used can be in any percent always requiring two or more of the above fiber types. The percentage and combination of blends is dependent on the application requirements.
This combination of systems provides a unique opportunity to apply liquid resins to a fibrous matrix, such as a cotton shoddy matrix, that is sensitive to line process strain and resistant to absorption due to density. The system viewed in whole, may include one or more of the following in various embodiments.
Additional Data is attached as Appendix A, noting the following:
The described system and methods are not limited to the specific embodiments described herein. In addition, components of each system and/or steps of each method may be practiced independent and separate from other components and method steps, respectively, described herein. Each component and method also can be used in combination with other systems and methods.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
indicates data missing or illegible when filed
The present application claims the benefit of the provisional patent application Ser. No. 61/739,376, filed Dec. 19, 2012, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61739376 | Dec 2012 | US |
