Methods for supplying fibrous insulating materials by injection under air pressure provide a generally economical method of insulating a desired space. Such methods are economical at least partly because relatively inexpensive fibrous materials such as cellulose, or mineral fibers, fiberglass and the like can be used, as described, for example, in U.S. Pat. No. 4,487,365 issued Dec. 11, 1984, to Sperber; U.S. Pat. No. 4,530,468 issued Jul. 23, 1985, to Sperber; U.S. Pat. No. 4,712,347 issued to Sperber; and U.S. Pat. No. 4,768,710 issued Sept. 6, 1988, to Sperber and also because of the relative speed with which the insulation can be injected under air pressure compared with the installation of batt-type insulation.
There are two primary methods for supplying fibrous insulating materials by injection under air pressure. In the first, insulation particles mixed with adhesive are inserted into the space between the outer and inner walls of the structure. Since it is desirable to "blow in" the insulation particles and adhesive mixture prior to the construction of the inner walls, a retaining means, as described, for example, in U.S. Pat. No. 4,712,347, by Sperber, issued Dec. 15, 1987, is typically used to retain temporarily the insulation between the wall framing until the inner wall can be constructed to act as a permanent retaining barrier.
The process of blowing-in fibrous insulation has at least one major drawback. The process typically produces insulation with non-homogeneous density. The nonhomogeneity is caused both by the later portions of blown-in insulation impacting and compacting the first portions of blown-in insulation and by the settling of the fibers over time. In general, compacted or densified fibrous insulation has a lower insulating capacity compared to less dense or uncompacted fibrous insulation. Although an adhesive can be used to assist in maintaining the loft of fibrous insulation, as described in U.S. Pat. Nos. 4,487,365; 4,530,468; and 4,712,347 above, the adhesive may have insufficient time to set, cure or dry before impaction from succeeding portions of insulation occurs and may have insufficient strength to withstand the force of impact from succeeding portions of blown-in insulation. Additionally, the adhesive by itself may not be sufficiently spread or mixed with the fibers to provide the desired separation of the fibers.
In the second method for supplying fibrous insulating materials by injection under air pressure, lofted fibers of insulation are mixed with a foam to provide a blown-in fibrous insulation which has a substantially homogeneous density, providing for uniformity of insulation, as disclosed in U.S. Pat. No. 4,768,710. The lofted insulation fibers are created by the mixture of substantially dry fibrous particles with pressurized air. Similarly, the foam is created by the mixture of a foaming agent with pressurized air. The foam and lofted fibers are then introduced into the mixing chamber of a nozzle. Although not discussed in the '710 patent, a single mixing hose is typically connected to the nozzle. The inside diameter of the mixing hose is greater than that of the nozzle outlet. In the mixing chamber and mixing hose, the foamed material is mixed with the lofted fibers so that the foam maintains the loft or the desired spreading of the insulation fibers relative to each other. The length of mixing hose can be approximately two feet. The mixture of fibers and foam material is carried under pressure away from the mixing hose into the desired space, but without any velocity, where the foam maintains the desired loft or spreading of the insulation fibers to achieve a uniform density of the insulation over time.
Like the first method, the apparatus and method of U.S. Pat. No. 4,768,710 has a significant limitation. The apparatus does not eject the foam/insulation mixture with sufficient velocity to cause the mixture to adhere to a surface, even though an adhesive material has been incorporated into the mixture. Rather, as in the first method, placement of the mixture requires the use of some means to retain temporarily the insulation between the wall framing until the inner wall can be constructed to act as a permanent retaining barrier.
In contrast to loose fibrous insulation, insulation comprising a solid "foam" is used in some applications. Although fibrous material can be incorporated into such foam as crystallization sites, fillers, reinforcements and/or pacifiers, as described in U.S. Pat. No. 4,402,892 issued Sept. 6, 1983, to Helser, it is the solid foam itself, rather than the fibers, which produces the insulation effect. To enable such insulation to fill a void, it is first produced in a fluent form and then cured or dried to form the solid foam. Thus, the fluent foam must be capable of substantial solidification into a permanent body. Materials which are capable of this solidification such as a cementitious material, as described in the Helser patent, or resin materials as described in U.S. Pat. No. 4,103,876 issued Aug. 1, 1978, to Hasselman, Jr. et al. and U.S. Pat. No. 4,135,882 issued Jan. 23, 1979, to Harkness et al. are typically more expensive than fibrous insulation materials. Furthermore, many solid foam insulation materials require relatively expensive and time-consuming additional steps to accomplish curing or drying, such as a heating step.
U.S. Pat. No. 4,447,560 issued May 8, 1984, to Piersol describes forming a fibrous sheet by agitating a mixture of a foamable solution and a slurry of binder-coated insulation fibers to homogeneously suspend the fibrous slurry. The present invention differs from the subject matter of the Piersol patent in several important respects. First, unlike the Piersol patent, the present invention does not utilize a slurry of fiber and binder materials but requires the use of pressurized air to provide spreading of insulation fibers to achieve a desired degree of fiber "fluffiness." Second, the foam material desired herein is already in its agitated state when it is mixed with the fibers. Third, the insulation mixture of the present invention is directly sprayed under pressure into a formed cavity at a building construction site; there is no formation of a batt-type insulation or a standard sheet of fibrous material. Finally, there is no step of heating for drying purposes after the insulation material is located in the cavity.