Polyurethane foam carpet underlay products are utilized to provide cushioning benefits for pedestrians since carpet is usually placed over hard floors, such as concrete or wood. Such carpet underlay thus should provide a uniform and even cushioning effect over the entire covered area. Furthermore, there are certain aesthetic qualities which are demanded in the marketplace for such carpet underlay products as concerns colorations and appearances. These demands have been met in the past through the utilization and introduction of colorants through one or more pipes or injectors, arranged consecutively and serially (if a plurality is present), through connections (feed lines, etc.) feeding to a manifold, and ultimately into binder compositions comprising the standard polyurethane reactants (polyols, such as ether triols, and the like, and isocyanates, such as methyl diphenyl diisocyanate, and the like, as merely examples; any standard polyol and isocyanate utilized to produce polyurethane in this industry may be used). The pipes or valve assemblies have been disposed in the past by merely creating a hole in the manifold to which the pipe or valve assembly is attached. The colorant would then be fed (by pressure or gravity, for instance) through the pipe or valve assembly and emptied into the binder stream travelling through the manifold. These colored compositions are generally mixed by a binder pump and sprayed onto scrap foam to form the desired carpet underlay product. Such a standard method has proven inefficient and problematic in the past since the through-pressure of the travelling binder stream is not always constant and thus the mere introduction at the walls of the manifold has not provided sufficient ability to thoroughly mix the colorant within the binder stream (in fact, the colorant remains in contact with the manifold wall rather than being "injected" into middle of the binder stream). This procedure thus leads to uneven coloring, discolorations, coagulation of binder and colorant, and the production of undesirable and potentially costly waste foam.
As a result, the demand for the introduction of a wide variety of colors in binder compositions for the production of polyurethane foam carpet underlay products has resulted in a significant move to blend-on-fly color dosing units based on the use of polymeric colorants. In this case color metering equipment is used to accurately dose two or more colors that are injected into the polyol stream and subsequently mixed in a binder pump to provide the correct shade and depth of color. The biggest advantage of this type of approach is that now an unlimited number of colors can be made from 1 to 5 "primary" colors blended on-the-fly. For example, a typical colored polyurethane product, carpet underlay, is colored and produced through a system based upon a binder/colorant shot process (i.e., color is introduced simultaneously with the start of a binder pump and stops when the pump is shut off, thus eliminating the introduction of additional color into the manifold). Changes from light and/or dark shades and color changes from one hue to another can be accomplished with a minimal amount of binder flush through the manifold thus reducing the amount of off-quality foam produced during the color change procedure. Thus, changes from one dark color to the next can usually be accomplished in relatively short distances minimizing the amount of foam that must be scrapped as a result of the color change. Light shades have proven to be more of a challenge since the color throughput is substantially lower causing the response time to increase before changes actually made in the system can take effect. As a result, a means was needed to reduce this response time to an acceptable level thus minimizing the length of time required to change from one color to the next even at low flow rates (approaching 2 grams per minute or less.)
A means was also needed to produce even colorations in the final product, as well as to possibly reduce the amount of coagulated binder/colorant (that is coagulated or crystallized portions of the colorant combined with the polyol and the isocyanate of the binder composition). Such a coagulant theoretically produces patches or areas of "hardness" within the carpet underlay product. As such a product desirably provides a uniformly cushioned, soft feel as a layer between the carpet and the hard floor underneath, any coagulated binder/colorant will produce unwanted, deleterious areas of "hardness."
Thus, it was necessary to develop a configuration and/or utilize, within this specific configuration, a specific valve assembly in order to facilitate effective on-the-fly polymeric colorant blending with even colorations in the final product and substantially reduced, if not eliminated, binder/colorant coagulant production. To do this it was first necessary to realize that the current standard configuration utilized either a single colorant "injector" (i.e., pipe, valve, etc.) on the dosing manifold, or a plurality of "injectors" aligned consecutively and serially on the manifold (i.e., one after the other), such that the "injectors" would merely be used to transfer colorant to a location in very close proximity to the manifold inner wall. Such a limited manner of "injecting" colorant resulted in the problems discussed above since the colorant would not become thoroughly mixed and, in conjunction with the laminar flow of the binder through the manifold, would basically remain in contact with the manifold rather than become thoroughly mixed within the binder stream. Thus, it was reasoned that the main problem with the traditional method of producing polyurethane foam could be alleviated through the utilization of a newly modified valve assembly which extends within the actual manifold rather than remains at a location outside the manifold. Accordingly, this invention provides apparatus for the production of polyurethane foam carpet underlay comprising a mechanism for the introduction of colorant within a binder composition; wherein said apparatus comprises a manifold comprising an inside surface and an outside surface, within which said binder composition and said colorants are mixed together, which leads to a binder pump; wherein said apparatus comprises at least one valve assembly through which said colorants are transferred from a feed line to said manifold; and wherein said at least one valve assembly is disposed within said manifold such that said at least one valve assembly is simultaneously in contact with both said outside surface and said inside surface of said manifold.
Furthermore, in other polyurethane producing procedures, colorants have traditionally been added strictly to the polyol component prior to its ultimate reaction with isocyanate to form the target polyurethane article (such as foam, carpet underlay, car bumpers, and the like). However, such formulators do not always produce colored polyol compositions since uncolored foam products are also desired by consumers. Thus, the polyol producer generally mixes and formulates the desired polyol/colorant compositions and ships such to its customer polyurethane producer. Polyol production generally is performed in a single dedicated mixing vessel for cost purposes. If a batch of polyol is to be colored, the formulator must thoroughly mix the polyol and colorant constituents in such a vessel. However, should a further polyol composition need to be produced without added colorant, the mixing vessel must be thoroughly cleaned after each production of polyol/colorant composition (especially when pigments are utilized). This cost-cutting thus has translated into limited choices of color since the formulator generally produces either uncolored or a single color of polyol (such as black, from a black pigment). Additionally, the color response time from the dispensing of colorant to the clear introduction of colorant within the target polyol composition is generally is very high with the systems now in use (i.e., valve assemblies attached to the outside of a manifold which introduce colorant into the manifold at the surface of the inner wall). For instance, and merely as one example, the following measurements were undertaken with the standard valve assemblies now utilized: Through a one inch manifold a polyol composition was pumped at about 466.5 grams per minute. Color was added at a rate of 11.1 grams per minute at an injection point eighteeen inches from a standard gear pump followed by an additional eighteen inches of pipe from the discharge port on the pump to an outlet. Upon actuation of the valve assembly to a dispense mode, a total time of 35 seconds was required before colorant was located within the polyol composition past the outlet. However, when the inventive valve configuration was practiced, a total time of seventeen seconds passed prior to colorant realization in the polyol composition. Furthermore, upon switching the traditional valve assembly (which permits colorant to travel down the manifold inner walls) to recirculation mode (thereby preventing the introduction of more colorant within the manifold), a total time of 120 seconds was measured before colorant disappeared from the polyol final product. Upon use of the inventive valve assembly, a total time of between 25 and 30 seconds was necessary for a full depletion of colorant within the target polyol. Thus, clearly, the introduction of colorant into the center of the binder stream afforded both quicker starting times and ending times (and thus a substantial reduction in the production of waste polyurethane).
The inventive valve assembly configuration provides a vast improvement to polyol formulators and ultimate foam producers in permitting greater flexibility in color choices with the facilitation of potentially costly clean-up efforts since the new valve-added manifold permitts the manufacture of all uncolored polyol compositions within the formulator's mixing vessel. The colorant can then be added directly to the polyol in its final shipping container through the utilization of the inventive valve/manifold assembly by permitting thorough mixing of the colorant and polyol through the introduction of the colorant directly into the stream of polyol (binder) during the transfer of the polyol from the mixing vessel into the shipping container (tote bin, tank truck, and the like). Since the valve assembly "injects" the colorant into the center of the transferred binder stream, the colorant will not appreciably coat the walls of the manifold or remain stagnant within the manifold (and thus no coagulation will occur).
The particular valves may be of any structure themselves; however, preferred valves are specific ball valves which comprise two exclusive channels to permit instantaneous switching from dispense to recirculation mode which are discussed in greater detail below. Also, a preferred, but not required radial configuration of a plurality of valve assemblies on the manifold has proven to be most effective in providing thorough and highly desirable colorations through the mixing of different colorants within the binder stream itself. This effectiveness is most likely due to the nearly immediate response time to an actuator signal each valve allows since they are equidistant from the same mixing binder pump. Such a configuration is particularly suited for introducing (such as by injection) colorants into target binder compositions (comprising polyols) for the ultimate production of target polyurethane foam products (most importantly carpet underlay) thereby allowing for a substantial reduction in potential foam waste due to low colorations or discolorations. Furthermore, as noted above, such a radial configuration substantially reduces the binding together of excess colorant and binder which may produce unsightly and uncomfortable areas of "hardness" in the foam underlay. The resultant product was thus thoroughly and evenly colored and exhibited an even cushioning over the entire article.
In addition, and as noted above, it has been found that the inventive valve assemblies may also comprise specific types of ball valves which comprise two mutually exclusive channels running through perpendicular planes of the ball, one remaining in the same plane from entry through one side of the ball until exiting the opposite side, the other entering the ball at one axis, and exiting at a point 90.degree. from the point of entry on a different axis. More particularly, the preferred ball valves utilized possess such mutually exclusive channels exhibiting the same bore sizes as well as the same bore sizes as the dispense port into the manifold. This ball valve facilitates quick and efficient movement of the valve from recirculation to dispense mode with minimal, if at all, leakage or loss of colorant. Such use of the ball valve also results in a rapid build up of pressure and hence almost instantaneous feed (and minimal, if any, pressure drop upon movement of the valve between modes). In addition to rapid initiation of color flow, it has been found that the exigencies of the situation also require the ability to almost instantaneously interrupt the flow of colorant even at high throughput pressure when the color was switched from dispensing mode back to the recirculation mode. This requirement theoretically prevents the "bleeding" of color back into the manifold when the need for color ends. The standard valve assemblies used today do not effectively address this problem. As such, the near immediate start and stop of color flow has been accomplished as a result of the utilization of the particular ball valves within the current inventive method, valve assembly configuration, and dosing apparatus.
Polymeric colorants (ie., polyoxyalkylenated colorants) such as those described in U.S. Pat. No. 4,284,279 to Cross et al., herein entirely incorporated by reference, have been used for a number of years to color polyurethane foams, including carpet underlays. Prior to the utilization of such polymeric colorants, pigment dispersions were the main source of polyurethane coloring compounds. Such dispersions have traditionally proven very difficult to handle, too viscous for use within standard injectors, highly staining and thus difficult to clean from standard injector equipment (without the need for environmentally unfriendly solvents), and very abrasive and thus potentially damaging to the delicate machinery associated with coloring polyurethane foam. As a result, polymeric colorants are widely accepted as the best materials for coloring polyurethane foam carpet underlay products.
In the past, custom blends of polymeric colorants were made ahead of time using two or more "primary" colors prior to incorporation within the target foam. The components would be mixed together using some type of agitator such as a mixer or a drum tumbler. Once the blend was of an appropriate shade it was transferred to a storage tank for further introduction within the foam substrate. Upon completion of coloring with a specific batch of polymeric colorant, the previously run color would have to be emptied from the storage tank; the tank would need to be cleaned; and then the next color to be run in the same tank would have to be charged in the tank. Cleaning of the tanks, feed lines (a.k.a. pipelines), etc., was facilitated due to the water-solubilily of the polymeric colorants (particularly as compared to pigments); however, the procedures followed were still considered labor intensive and not cost efficient. The general practice was then modified to maintain a dedicated tank for each separate color (shade) that was to run. This led to a number of inefficiencies and limitations that were not desirable if a foam manufacturer was to adequately meet demands in the market place.
Polymeric colorants, such as those cited above in Cross et al., were designed to be totally miscible with one another as well as with most polyols, one of the two main ingredients used to produce polyurethane materials (isocyanates being the other). Pigment dispersions, on the other hand, are particulates dispersed in some type of liquid carrier. They require a high degree of agitation before they satisfactorily blend together to provide a uniform color. As a result, the short amount of time that the polyol and colorant are mixed in the typical foam-producing apparatus'binder pump is not sufficient to permit an adequate mixing of components to insure a single, homogeneous coloration throughout the target foam.
A configuration of this typical colorant production line for colored carpet underlay foam is depicted in FIG. 1. This standard coloring system itself generally consists of 1 to 5 "primary" color storage tanks (three of which are depicted as 12a, 12b, 12c in FIG. 1) each feeding a stream of colorant through feed lines 13a, 13b, 13c to at least one (per feed line 13a, 13b, 13c) positive displacement spur gear pump 15a, 15b, 15c coupled to a variable speed motor/drive 14a, 14b, 14c (such as available from Viking). The motor/pump combinations 14a, 15a, 14b, 15b, 14c, 15c are typically run continuously in either recirculation or dispense mode (depending on the position of a 3-way valve 11a, 11b, 11c) to minimize the time required to spool up the motor 14a, 14b, 14c to the proper rpm and to ultimately achieve the pressure required to initiate color flow into a pre-mix manifold 8 through serially configured 3-way valves 11a, 11b, 11c [and/or injectors (not illustrated)]. The throughput pressures of each line are typically measured through the utilization of pressure gauges 16a, 16b, 16c attached to each feed line 13a,13b,13c from the pumps 15a,15b,15c to each 3-way valve 11a, 11b, 11c. The typical 3-way valves 11a, 11b, 11c are air actuated and used to direct the flow of colorants from the recirculation feed lines 17a, 17b, 17c to the dispense lines (not illustrated) to the manifold 8 when color flow to the manifold 8 is required. The colorants will mix with a stream of binder composition 10 comprising the polyurethane reactants (polyol and isocyanate, as well as other potential additives). From the manifold 8, the binder composition and colorants are moved to the binder pump 9 for further and more thorough mixing of the resultant binder/colorant composition. The resultant composition is then sprayed onto a substrate (such as scrap foam, not illustrated) to produce the desired polyurethane foam carpet underlay product (not illustrated). Although this configuration has proven effective in the past, there remain a number of problems associated with this procedure which have heretofore been unresolved.
For instance, the market place demands that a polyurethane producer be able to provide shots of binder to produce dark shades as well as light shades with a variety of hues and at differing polyol flow rates. Since color is metered volumetrically, a wide range of color flow rates are required to insure low enough flow for a minor component in a light shade. In addition, the polyol flow rates can be as low as 14 kg/min and as high as 55 kg/min [color loading is generally stated in weight percent of binder (wt. %)]. As the rate at which the polyol flow is reduced so must the color rate be reduced to maintain the same wt. %. For most polyurethane products manufactured in the United States, the color delivery systems must be able to provide color flow as low a 2 grams/min and as high as 3000 grams/min or more. The rate at which color begins to flow when pumping 3000 grams/minute is generally very different than pumping 2 grams/min until the present invention is incorporated, for example. Prior to this point in time, the general approach was to use a smaller diameter line for the low flow range. Unfortunately, there are distinct limitations on such a small diameter (small bore) feed line, most notably the resultant throughput pressure drop from pumping material several feet through a small diameter line.
Furthermore, the typical valves utilized in polyurethane rebond (i.e., with the use of a binder component subsequently mixed with isocyanate) foam coloring systems have a three-way air actuated ball valve assembly (18 in FIG. 2) that is positioned approximately three to six feet from the binder composition manifold (8 in FIG. 1) (such as 11a, 11b, 11c in FIG. 1). Due to the configuration of the available ball valves, the corresponding feed lines are generally arranged serially and consecutively on the outside of the manifold (8 in FIG. 1). As provided by the representation of a standard three-way ball valve assembly 18 in FIG. 2, material metered by the pump enters the top of the three-way ball valve 19 from the storage tank feed line 20 and exits either through the recirculation side 25 or the dispense side 22 depending on how the ball is oriented. FIG. 2 depicts the ball valve 19 when it is oriented in the recirculation mode. Once it is desired to change from recirculation to dispense and back to dispense the ball valve 19 must typically rotate 180.degree. from one side of the ball valve 19 to the other (although there are some apparati which utilize a 90.degree. ball valve rotation) through the movement of an actuator (not illustrated) attached to an actuator pin 23 which, in turn, fits into an indentation (not illustrated) within the ball valve 19. Furthermore, the typical ball valve 19 comprises a single channel 21 to accommodate the flow of colorant to either the recirculation side 25 or the dispense side 22. This single channel 21 is configured at a right angle and thus may contribute to laminar flow problems by requiring the colorant liquid to radically change direction, thereby altering the pressure over the total liquid mass (and thus producing non-uniformity of pressures over the entire liquid colorant).
In addition to this typical 3-way valve, a device must be used to inject color away from the wall of the manifold to insure adequate subsequent mixing (i.e., to reduce the problems associated with laminar flow through a feed line having a larger diameter than the 3-way valve). Ideally, such a device should function as a check valve to maintain pressure in the line between the valve and the manifold and to stop color flow when switching from dispense to recirculation. Such devices must maintain pressure after the dispensing unit is returned to recirculation mode otherwise the pressure drops below the "cracking" pressure of the check valve spring which will result in even longer startups which, in turn, may translate into cost overruns, potentially greater amount of off-quality colored foam, or foam containing numerous undesirable "hardness" areas. Additionally, the resultant pressure drop must be acceptable across a broad delivery range for such injectors to alleviate any other related pressure difference problems. Also, such check valves are effective in preventing binder from entering valve assembly from the manifold. As such, the check valves are prone to plugging due to the hardening of the binder in the highly restrictive space. There have been no developments providing such desired improvements or remedies to improve upon and/or correct these problems accorded the industry by the prior art.