Abstract:
The present invention relates to a method for improving the thermal performance of fibrous glass insulation in the admix recycling of the insulation, which includes the use of corrugated hose in the recycling process.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Insulation assemblies and, more particularly mineral fibers, including fibrous glass insulation assemblies are known in the art. Fibrous insulation assemblies are used for insulating buildings. The insulation assemblies take the form of batts or rolls which are compressed for packaging and transport. Many prior art insulation assemblies are sized along their side edges by slicing or cutting the side edges to the desired shape and width.  
           [0002]    In contrast to textile and reinforcement fibers, glass wool fibers are produced by processes which generate noncontinuous fibers of random lengths. Glass wool products are best known for their properties such as thermal or acoustical insulation, and as filtration media.  
           [0003]    Various glass compositions have been used for wool products. Factors affecting the choice of the glass composition are the availability and cost of the raw materials, the melting cost, the forming process used (glass liquidus and viscosity requirements), and the product properties (durability, resilience). For example, the low-cost rock and slag wool compositions have a high liquidus and therefore cannot be formed by the rotary process. These compositions are fiberized instead by an air blast process or a rotating disk or multiple rotating drum process, resulting in a high-shot (droplets of glass that have not been fiberized) content.  
           [0004]    Due to the high surface area of the wool fibers, the glass must be resistant to water attack and, for some applications have good chemical durability.  
           [0005]    The most familiar application for wool products is for thermal insulation. The random intertwining of many small fibers effectively traps air within the insulation pack, thus providing the insulating properties. Also, the fibers tend to block radiative heat transfer due to their optical properties. The characteristics of fire resistance, chemical stability, and resistance to moisture attack make glass an ideal material for this application.  
           [0006]    The same ability to trap air makes glass fiber a suitable acoustical insulation. This has led to the use of glass fiber as ceiling and wall panels in buildings and vehicles, and to its use in air handling systems where noise control is important.  
           [0007]    The fiber diameter of the wool products is an important indicator of its performance. In general, finer fiber products are more costly to produce, but provide better thermal and acoustical performance per pound of glass. Current technology can produce average fiber diameters that range from about 1 to 25 um. In a wool pack, the fiber diameter will vary considerably from the average value.  
           [0008]    In most glass wool products, a phenolic binder is added during the manufacturing process to bond the mat together. Depending on the application, the amount of binder can vary between 4 and 15 percent by weight.  
           [0009]    The present method of use is directed to an improvement in the recycling of fibrous glass insulation, in order to reduce thermal conductivity and improve product appearance.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention relates to the use of corrugated hose for admix recycling in fibrous glass insulation, in order to reduce thermal conductivity and improve product appearance. The use of corrugated hoses serves to improve the opening of admix nodules, and reduces their density. By “corrugated” it is meant shaped into folds, or parallel and alternating ridges and grooves. Advantages of the method of the present invention include (1) a more uniform appearance of product with less color and density contrast between virgin fibers and recycled admix, and (2) an improved thermal performance/reduced thermal conductivity. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a diagrammatic view showing corrugated hoses in place of smooth metallic pipes in the admix recycling circuit. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    The following is a preferred embodiment of the present invention:  
         [0013]    In the forming section where a glass mat is formed, virgin fiber is produced and liquid binder applied to the fiber. Pieces of recycled fiber mat are also added in the forming section. The formed glass mat composed of virgin binder, uncured binder, and recycled fiber mat is then conveyed from the forming section to the curing oven where the oven cures the binder and sets the fiberglass mat to the proper thickness. The recycled fiber mat is conveyed to the forming section from the edge trim section near the exit of the curing oven. Referring to FIG. 1, after the cured, hot fiberglass mat  10  exits the curing oven, it is cooled and then conveyed to the edge trim slitter section. The “slitters” on each side of the line then saw off the rough edges of the mat  11  and  12  to produce material  13  with square sides. The rough edge strips from the slitters are cut into small pieces in hammermills  14  and  15  and conveyed by edge trim fans  16  and  17  to the forming section (approximately 150 to 300 feet in length) through a corrugated hose  18  and  19 , rather than a smooth pipe. The admix is the cut, cured binder and fiber that is conveyed to the forming section.  
         [0014]    Note that after the admix handling fans, corrugated hoses are installed instead of the standard smooth metallic pipes for the admix recycling circuit.  
         [0015]    The use of corrugated hoses improves the opening of admix nodules, and reduces their density. Advantageous outcomes include (1) a more uniform appearance of product, with less color and density contrast between virgin fibers and recycled admix, and (2) an improved thermal performance/reduced thermal conductivity.  
         [0016]    The following test results (ASTM C518 at a mean temperature of 75 degrees F.) demonstrate the effectiveness of the present invention in terms of thermal performance improvement, using building insulation product:  
                                                                                           Admix with               Corrugated           Standard   Hose                (Admix with Smooth Pipe)   A   B                        Insulation Product   0.82   0.82   0.79       Density (lb./ft 3 )                  
 
         [0017]    [0017]                                                                                           Admix with           Standard   Corrugated Hose                (Admix with Smooth Pipe)   A   B                        Thickness (in.)   3.5   3.5   3.5       Thermal Conductivity   0.271   0.268   0.271       (BTU inch/hr.ft 2  °  F.)       R-value   12.91   13.08   12.91       (hr.ft 2  ° F./BTU)                    
         [0018]    Thus, for the same R-value as the standard approach, approximately 3.7% less material is required. This represents a significant improvement over conventional systems.  
         [0019]    While this invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.