Patent Application
20090140464
The invention relates generally to the field of curing a binder on fibrous insulation. A mass of numerous insulation fibers are bonded to one another with a thermoset binder, which forms a lofted fibrous insulation having a desired density and a rated, R-value thickness. One type of fibrous insulation is adapted for filling cavities in walls and ceilings of a building, thus, lowering the heat transfer rate through the insulation. Another type of fibrous insulation is a duct liner for lining a ventilation air duct. The duct liner lowers the heat transfer rate through the insulation, and further, reduces noise associated with air flow through the air duct. The fibrous insulation can be covered with a facing layer, for example, in the form of a flexible sheet or web, that provides an air stream surface and/or that controls vapor transmission through the insulation.
During manufacture of fibrous insulation, a binder is dispersed among numerous insulation fibers, and a collective mass of the insulation fibers are assembled on a conveyor to form a lofted fibrous insulation. The fibrous insulation is conveyed by the conveyor through a curing oven for curing the binder. The binder is either a liquid based binder, usually in an emulsion or solution, or a dry binder, usually in powder form. Alternatively, the dry binder is a thermoset polymer in fibrous form that is dispersed among the insulation fibers. The binder is cured by heating the binder to its curing temperature. The binder undergoes a phase change to attain a thermoset state. Further, the binder bonds the insulation fibers to one another in the lofted fibrous insulation.
To cure the binder, heated gas is directed to flow into the fibrous insulation. The temperature of the heated gas corresponds to a curing temperature of the binder. However, the free flow of heated gas to the interior of the fibrous insulation is resisted by a thickness of the fibrous insulation and by the density of the fibrous insulation. Consequently, the binder on insulation fibers within an interior of a thick fibrous insulation will cure at a slower curing rate than the binder on insulation fibers at or near an exterior of the fibrous insulation. A fibrous insulation formed by a known air laid process will have a uniform density of the insulation fibers throughout. However, a known accumulation process of making a fibrous insulation assembles the insulation fibers according to an uneven distribution, creating short-cut air flow paths among corresponding insulation fibers in the fibrous insulation. When heated gas is directed into the fibrous insulation to cure the binder, the short-cut air flow paths become hot spots. The binder on the corresponding insulation fibers will cure at a high curing rate due to the hot spots, while the binder on other insulation fibers will cure at a slow curing rate.
There is a current need for a method of curing a binder on insulation fibers of a fibrous insulation, by compensating for a slow curing rate of the binder on insulation fibers located within an interior of the fibrous insulation. Further there is a current need for a method of curing a binder on insulation fibers, by compensating for a high curing rate of the binder on corresponding insulation fibers among which short-cut air flow paths are present.
The invention relates to a method of curing a binder on insulation fibers of a fibrous insulation by, adjusting a temperature of a heated gas to a binder curing temperature, and directing the heated gas to flow in an adjusted ratio of, downwardly into the fibrous insulation and upwardly into the fibrous insulation, to cure the binder and to compensate for a slow curing rate of the binder on corresponding insulation fibers within an interior of the fibrous insulation.
According to an embodiment of the present invention, a method of curing a binder on insulation fibers of a fibrous insulation comprises, directing a flow of the heated gas, either as an upward flow into the fibrous insulation, or as a combination of the upward flow and a downward flow into the fibrous insulation, and exhausting the heated gas to cool the binder.
According to a further embodiment of the present invention, a method of curing a binder on insulation fibers of a fibrous insulation comprises, recirculating at least a portion of the heated gas flow to form a recirculating gas flow; and combining flame heated ambient air with the recirculating gas flow to form the heated gas flow that is directed into the insulation fibers.
According to a further embodiment of the present invention, a method of curing a binder on insulation fibers of a fibrous insulation comprises, directing a flow of the heated gas, either as an upward flow into the fibrous insulation, or as a combination of the upward flow and a downward flow into the fibrous insulation, to cure the binder and to compensate for a slow curing rate of the binder on corresponding insulation fibers within an interior of the fibrous insulation, followed by, exhausting the heated gas, and directing cooling air onto the fibrous insulation to cool the binder on corresponding insulation fibers among which short-cut air flow paths are present.
Further, the invention relates to a fibrous insulation having insulation fibers, and a binder on the insulation fibers being cured by, adjusting a temperature of a heated gas to a binder curing temperature, and directing the heated gas to flow in an adjusted ratio of, downwardly into the fibrous insulation and upwardly into the fibrous insulation, to cure the binder and to compensate for a slow curing rate of the binder on corresponding insulation fibers within an interior of the fibrous insulation.
According to an embodiment of the present invention, a fibrous insulation has insulation fibers and a binder on the insulation fibers, the binder being cured by a process comprising: recirculating at least a portion of the gas flow to form a recirculating gas flow; and combining flame heated ambient air with the recirculating gas flow to form the gas flow that is directed into the insulation fibers.
Embodiments of the invention will now be described by way of example with reference to the following detailed description and the accompanying drawings.
In the exemplary process illustrated in
Further,
In the heater (210), a burner (212), of natural gas, for example, heats the ambient air and reheats the recirculated gas. The reheated, recirculated gas combines with the flame heated ambient air to become the heated gas that is supplied to the heating zone chamber (102). In the heater (210), the heated gas is heated to at least a curing temperature of the binder, preferably, somewhat higher that the curing temperature of the binder. The temperature is adjusted by an adjustable control (214) on the burner (212) to regulate the flame. A downstream end of the heater (210) disclosed by
With further reference to
Further, heated air is supplied to the top inlet duct (112a). The heated gas is directed downwardly into the fibrous insulation (108). Initially, the binder on the fibrous insulation (108) is heated by a heated gas flow ratio of 1:1, of downwardly directed flow to upwardly directed flow. The fibrous insulation (108) emerging from the heating zone chamber (102) is inspected for complete curing throughout the fibrous insulation (108).
For an embodiment of the fibrous insulation (108) having a relatively large thickness, and/or high density, the binder cures at a low curing rate. When inspection reveals that curing of the binder on an interior of the fibrous insulation (108) is incomplete, the ratio is adjusted such that the flow rate of either the upward or downward flow is increased to penetrate the heated gas farther into the interior of the fibrous insulation (108), to completely cure the binder on the interior of the fibrous insulation (108).
When one or more surfaces of the fibrous insulation (108) is covered by respective facing layers (300) and/or the reinforcement layer (304), the gas flow ratio is adjusted to compensate for, and overcome, an increased resistance to gas flow due to the corresponding layer (300) and/or the layer (304). For example, the gas flow ratio is adjusted to increase the upward flow into the fibrous insulation (108) while a top surface of the fibrous insulation (108) is covered with a facing layer (300). Further, for example, the gas flow ratio is adjusted to increase the downward flow into the fibrous insulation (108) while a bottom surface of the fibrous insulation (108) is covered with a reinforcing layer (306). Further, for example, the gas flow ratio is adjusted for directing the gas flow as a combination of the upward flow and the downward flow while a top surface of the fibrous insulation (108) is covered with a first facing layer (300), and a bottom surface of the fibrous insulation (108) is covered with a second facing layer (300).
Cooling air flows in the cooling zone chamber (104) to cool the fibrous insulation (108). For an embodiment of the fibrous insulation (108) that has hot spots revealed by inspection of the fibrous insulation (108), the binder can be cooled to its thermoset state by cooling the fibrous insulation (108) with the cooling air. However, when the hot spots are required to be cooled, while a remaining portion of the binder remains uncured, then, one or more subsequent stages of the curing oven (100), as required, will cure the remaining portion of the binder.
The curing oven (100) is provided with multiple stages, each stage having a heating zone chamber (102) and a cooling zone chamber (104). In a first stage, hot spots are produced by heated gas flowing in short-cut air flow paths among corresponding insulation fibers in the fibrous insulation. The binder on the corresponding insulation fibers will cure at a high curing rate due to the hot spots, and is heated to a curing temperature, in a first stage heating zone chamber (102), followed by being cooled in a first stage, cooling zone chamber (104). The binder undergoes a phase change to a thermoset state. The remaining portion of the binder on other portions of the fibrous insulation (108) may remain uncured. In each following stage, an additional portion of the binder is heated and cooled, i.e. cured, to a thermoset state, such that, in one or more stages, as required, the remaining portion of the binder becomes cured to a thermoset state. The binder that has previously attained a thermoset state is unchanged by subsequent stages of the curing oven (100), which allows substantial heat transfer from the heated air to the uncured binder.
For an embodiment of the fibrous insulation (108) having a relatively large thickness, and/or high density and/or is covered on one or more major surfaces by respective facing layers (300) and/or reinforcing layer (304), the binder cures at a low curing rate. When an inspection reveals that a remaining portion of the binder in the interior of the fibrous insulation (108) is uncured, then multiple stages of the curing oven (100), as required, perform curing of the remaining portion of the binder.
In a first stage, the binder on the outer sections of the fibrous insulation (108) is heated and cooled to a thermoset state. The remaining portion of the binder on other portions of the fibrous insulation (108) may remain uncured. In each following stage, an additional portion of the binder is heated and cooled, i.e. cured, to a thermoset state, such that, in one or more following stages, as required, the remaining portion of the binder becomes cured to a thermoset state. The binder that has previously attained a thermoset state is unchanged by subsequent stages of the curing oven (100), which allows substantial heat transfer from the heated air to the uncured binder.
Embodiments of the fibrous insulation (108) have a density from 0.3 pcf (pounds per cubic foot) to 6 pcf, and more preferably from 1.0 pcf to 3 pcf. The thickness thereof is ⅛ inch to 8 inches, and more preferably form 1.0 inches to 6 inches. A continuous facing layer (300) is attached to and covers, a bottom, major surface of the fibrous insulation (108), a top, major surface, or both the bottom major surface and the top major surface. The line speed conveying the fibrous insulation (108) through the heating zone chamber (102) varies from 10 feet per minute to 100 feet per minute. The air distribution is divided between upwardly directed air and downwardly directed air according to a ratio of 20%, 30%, 40% and 50%, which are increments of 10%.
The disclosure of every patent, patent application, and publication cited herein is hereby incorporated herein by reference in its entirety.
While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention can be devised by others skilled in the art without departing from the true spirit and scope of the invention. The appended claims include all such embodiments and equivalent variations.
This application is a Divisional of U.S. patent application Ser. No. 10/939,277, filed Sep. 10, 2004 (D0932-00475), which is related to U.S. patent application Ser. No. 10/851,535, filed May 21, 2004 (D0932-00463), which is a continuation in part of U.S. patent application Ser. No. 10/781,994, filed Feb. 19, 2004 (D0932-00426), which is a continuation-in-part of the following copending U.S. patent applications: U.S. patent application Ser. No. 10/689,858, filed Oct. 22, 2003; U.S. patent application Ser. No. 09/946,476, filed Sep. 6, 2001; and U.S. patent application Ser. No. 10/766,052, filed Jan. 28, 2004 (D0932-00404); which are commonly assigned and hereby incorporated by reference. This application is also related to U.S. Pat. No. 6,673,280, issued Jan. 6, 2004 (D0932-00257); U.S. patent application Ser. No. 10/782,275, filed Feb. 19, 2004 (D0932-00385); U.S. patent application Ser. No. 10/806,544 filed Mar. 23, 2004 (D0932-00403); and U.S. patent application Ser. No. 10/823,065 filed Apr. 12, 2004 (D0932-00405), which are also commonly assigned and hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10939277 | Sep 2004 | US |
| Child | 12367825 | US |
