Patent Application
20090000245
Currently the manufacture of bulky and/or heavy laminated panels for use in building construction requires a large area for manufacturing. In addition to the bulk associated with the material in-process, the area required for manufacturing is increased by any process step requiring the material be staged for a long period of time. For a given throughput of material, the area needed increases with additional processing steps and with a longer processing time at any step.
For example, the laminated structure disclosed in the aforementioned U.S. Pat. No. 7,181,891 comprises two external layers of a non-metallic material (which in one embodiment are sheet gypsum), and an internal constraining layer, attached to each other by adhesive layers of viscoelastic glue. In some embodiments other materials are incorporated between the outer gypsum layers. In one embodiment the process of manufacturing a laminar structure, for example the structure disclosed in the '891 patent, includes drying a completed structure whilst pressure is applied to the structure. Depending upon the materials that make up the laminar structure, a dwell time (defined as the time required for a single process step) of several hours to a few days is required for the adhesive to properly dry, during which time other similar individual structures may be constructed which also require a dwell time of several hours to a few days to dry. The long drying time is due to the time required for liquid in the adhesive to soak into the gypsum sheets, the gypsum sheets then transporting the liquid to the surrounding environment via evaporation. A significant volume of material is staged at the drying step in the described construction sequence, the volume depending upon the production rate. As a result, a large drying chamber corresponding to the volume of a single structure multiplied by the finished product throughput desired and the dwell time of the instant step is required. Further, some steps of the manufacturing process may require that the drying chamber be maintained at a specified elevated temperature and low relative humidity, an energy intensive requirement.
For example, a production demand of one thousand finished four-foot by eight foot by one-inch structures per day, with a dwell time at a certain step requiring forty-eight hours of drying at a constant temperature of 120 to 140 degrees Fahrenheit, a relative humidity of about thirty per cent, and a constant airflow requires a staging area providing the required environmental conditions for two thousand structures at any given time, such staging area providing a minimum of 25 feet of vertical clearance on an approximately 25 foot by 45 foot footprint, amounting to 28,125 cubic feet of conditioned space. When manufacturing demands more than one thousand finished panels per day, even more drying volume is required. Any other process steps also requiring significant dwell time similarly increase the facilities needed for a given manufacturing throughput. A long cycle time, defined as the time required to construct a finished structure from start to finish, also extends the time required for a manufacturing operation to respond to an increase in demand for the manufactured product.
What is needed is a manufacturing method for a laminar structure wherein intermediate process staging of product during manufacture is minimized.
A laminar structure comprising a sandwich of a plurality of materials is constructed using process methods wherein the dwell time at certain steps is reduced from hours or days to a few minutes. In one embodiment adhesive is dried prior to adding any additional layers to the laminated build-up, eliminating the lengthy process step of drying the complete laminated structure. The adhesive is dried by blowing gas across the surface of the specifically formulated adhesive immediately after the adhesive is applied, forming a pressure sensitive adhesive (“PSA”). The next layer in the sandwich may then be applied with no further drying time required. In one embodiment the individual process dwell times and total cycle time are shortened enough to permit construction of complete laminar structures using a conveyor belt type assembly line apparatus, wherein no in-process material is staged or stacked up.
A laminar substitute for drywall comprises a sandwich of two outer layers of selected thickness gypsum board or other material which are glued to each other, using a sound dissipating adhesive wherein the sound dissipating adhesive is applied in a certain pattern to all or less than all of the interior surfaces of the two outer layers. In one embodiment, the adhesive layer is a specially formulated QuietGlue 320™, which is a viscoelastic material, of a specific thickness. QuietGlue 320™ is available from Serious Marterials, Inc., of Sunnyvale, Calif. Typically, QuietGlue 320™ is made of the materials as set forth in Table 1.
The preferred formulation is but one example of a viscoelastic glue. Other formulations may be used to achieve similar results and the range given is an example of successful formulations investigated. Formed on the interior surfaces of the two gypsum boards, the adhesive layer is about 1/16 inch thick. In various embodiments a differing number of layers of material of differing composition are sandwiched between the outer gypsum boards, each layer glued to adjoining layers by PSA. In the following discussion “adhesive”, “glue”, and “PSA” may be used interchangeably to refer to a layer of material in the context of a laminar structure sandwich. In this written description, “PSA” always refers to a layer of viscoelastic glue which has been dried to form a viscoelastic pressure sensitive adhesive.
Referring to
Next, the adhesive 204 is dried at step 106, so that the resulting moisture content in the adhesive is no greater than five percent by weight.
In one embodiment, a layer of viscoelastic glue at a thickness between one thirty second inch ( 1/32″) and one eighth inch (⅛″) on a panel of material four feet (4′) by eight feet (8′) was subjected to a flow of ambient air (typically between nineteen degrees centigrade (19° C.) and twenty four degrees centigrade (24° C.) at about fifty thousand cubic feet per minute (50,000 ft3/minute). The initial moisture content was about thirty percent (30%) by weight and after about five minutes of air flow the moisture content had been reduced to about five percent (5%) by weight.
A variety of methods may be used to dry the adhesive 204. In one embodiment the sandwich with exposed adhesive 210 is passed under a gas diffuser, wherein a volume of gas, for example between twenty to fifty thousand cubic feet per minute of air, is provided through openings in the diffuser. In some embodiments the provided gas is ambient air. In other embodiments the provided gas is preheated and/or dehumidified air. The gas-blowing system comprises a plenum chamber (not shown) for receiving pressurized gas from a blower, the pressurized gas subsequently flowing out through openings in the diffuser onto the surface of the exposed adhesive.
In one embodiment the intermediate panel sandwich 210 is moved on a conveyor belt 208 at ten feet per minute under a gas diffuser panel 400, wherein the diffuser 400 is four feet wide and twenty-four feet long (in the direction of belt travel). The adhesive is therefore exposed to the flowing gas for approximately 2.4 minutes. The exact exhaust area and shape of the diffuser 400 and the openings are not critical, providing the exhaust area of the diffuser 400 permits the desired gas flow, and provided further that the exhaust area of diffuser panel 400 is low enough such that the plenum chamber has adequate back pressure to provide an approximately even flow of gas out of the diffuser.
In one embodiment wherein a conveyor belt is not used, the intermediate panel sandwich 210 is placed upon a work surface 208, which may or may not be the same work surface upon which the panel 210 was placed for application of the adhesive 204, and wherein a diffuser 400 approximating the size and shape of the panel sandwich 210 and approximately aligned over the panel sandwich blows gas over the exposed adhesive, for example air at approximately seventeen cubic feet per second. An important parameter in the process is the degree of dryness of the adhesive attained in transforming the adhesive 204 into a PSA. For a specific implementation according to the method of the present invention, the combination of drying time, gas flow rate, diffuser panel 400 opening area, temperature and humidity of the gas provided through the diffuser 400, and the thickness of the adhesive 204 are adjusted to provide a suitable liquid content in transforming the adhesive 204 into a PSA, for example five per cent liquid by weight as measured with a moisture sensor such as the MW 3260 microwave moisture sensor manufactured by Tews Electronik of Hamburg, Germany. Assuming these factors are reasonably constant, the drying time is used as a predetermined time for drying step 106. If the adhesive is completely dried the next material in the sandwich may not stick to it. A liquid content of approximately five percent provides a tacky adhesive that has good adhesion characteristics but does not require further drying after the sandwich is assembled.
Referring to
The fully-assembled laminated structure 300 is pressed together at step 114. In one embodiment the laminated structure 300 is passed under a six-inch diameter roller (or the roller may instead by passed over the laminated structure 300) weighing approximately fifty pounds at approximately ten feet per minute. Following the application of pressure at step 114 the laminated structure 300 is complete and ready for shipping; no further drying or other manufacturing process step is required.
While the process has been described as drying the viscoelastic glue to essentially create a viscoelastic pressure sensitive adhesive, the process can also be used to partially dry the viscoelastic glue thereby to shorten the time that the stacked structure, when fully assembled, must be placed in a drying chamber to remove additional moisture from the viscoelastic glue used to join together the several layers of material.
The foregoing description of some embodiments of the invention has been presented for the purposes of illustration and description. The description is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to one skilled in the relevant art.
Reservation of Extra-Patent Rights resolution of Conflicts, and Interpretation of Terms
If any disclosures are incorporated herein by reference and such incorporated disclosures conflict in part or whole with the present disclosure, then to the extent of conflict, and/or broader disclosure, and/or broader definition of terms, the present disclosure controls. If such incorporated disclosures conflict in part or whole with one another, then to the extent of conflict, the later-dated disclosure controls.
Given the above disclosure of general concepts and specific embodiments, the scope of protection sought is to be defined by the claims appended hereto. The issued claims are not to be taken as limiting Applicant's right to claims disclosed, but not yet literally claimed subject matter by way of one or more further applications including those filed pursuant to 35 U.S.C. §120 and/or 35 U.S.C. §251.
Unless expressly stated otherwise herein, ordinary terms have their corresponding ordinary meanings within the respective contexts of their presentations, and ordinary terms of art have their corresponding regular meanings
This application is related to commonly-assigned U.S. patent application Ser. No. 10/658,814 filed 8 Sep. 2003, by K. Surace and M. Porat, now U.S. Pat. No. 7,181,891, issued 27 Feb. 2007 titled “ACOUSTICAL SOUND PROOFING MATERIAL AND METHODS FOR MANUFACTURING SAME” and to U.S. patent application Ser. No. 11/734,770 filed 12 Apr. 2007 by B. Tinianov, titled “ACOUSTICAL SOUND PROOFING MATERIAL WITH CONTROLLED WATER-VAPOR PERMEABILITY AND METHODS FOR MANUFACTURING SAME”, which are incorporated herein by reference.
