Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1998-04-17
2001-10-09
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S361000, C524S297000
Reexamination Certificate
active
06300400
ABSTRACT:
The invention relates to adhesives for use in construction.
BACKGROUND OF THE INVENTION
Adhesives are widely used in construction applications. For example, in the fabrication of wall systems (i.e., wallboard and wall frame assemblies), the industry typically constructs the wall frame on a horizontal work table and applies an adhesive to framing members of the wall frame. The adhesive is applied around the perimeter and in the “field” of the wall assembly. The field of the wallboard is the area within the perimeter of the wallboard. After application of the adhesive, 4 foot by 8 foot sections of wallboard (e.g., gypsum board) are placed onto the adhesive-coated framing members. The wall section is then raised to a vertical position for storage or use in constructing a house.
Fasteners (i.e., staples, screws, or nails) often are placed around the perimeter and in the field of the wallboard to provide additional strength to the assembly. By using fasteners, the wallboard and wall frame assembly can be raised almost immediately after the board is placed onto the adhesive on the framing member. The fasteners in the field in particular help avoid “wall pops.” Wall pops occur because the wallboard and wall frame assembly may flex and distort when raised to a vertical position. Wall pops can cause the wallboard and wall frame assemblies to become loose and vibrate or rattle. If the wall pops are severe, wall repairs can be required.
The presence of fasteners in the field of the wallboard can cause various aesthetic problems. For example, the fastener has to be covered up by hand-applied overcoating, which requires additional manufacturing time and compromises the appearance of the finished wallboard and wall frame assembly.
The suitability of an adhesive for particular uses can be determined from the open time and green strength of the adhesive. “Open time” is the length of time that the adhesive is wet to the touch after applying the adhesive to a support. “Green strength” refers the load that the adhesive can bear at a particular time after application of the adhesive to a surface.
SUMMARY OF THE INVENTION
In one aspect, the invention features to a water-based adhesive including water, a binder, and a particulate filler. The adhesive has a green strength sufficient to support a 4 foot by 8 foot wallboard on a wall frame without fasteners in the field of the wallboard within 15 minutes, and preferably within 10 minutes, of applying the adhesive to the wallboard and wall frame.
For purposes of this application, green strength is determined by the shear strength test by the method described in AFG-01 “Adhesives for Field-Gluing Plywood to Wood Framing” (section 5; American Plywood Association), where a gypsum board is used in place of the plywood. In this method, a 2 inch by 2 inch section of plywood is bonded to the center of a 3 inch by 3 inch gypsum board with the adhesive. A loading rate of 0.2 inches per minute is applied to the board assembly. The strength is checked in time intervals (i.e., every 5 minutes). When the paper on the gypsum board tears, adequate green strength is achieved. A shear strength, according to this procedure, within 15 minutes of applying the adhesive to the wallboard and wall frame of between 5 and 15 pounds for the purpose of this application is sufficient to support a 4 foot by 8 foot wallboard on a wall frame without fasteners in the field of the wallboard.
The open time of the adhesive greater than 5 minutes, preferably greater than 10 minutes. For purposes of this application, open time is determined by measuring the percent of adhesive transference between two boards according to the method described in ASTM C-557, sections 4 and 6. In this method, a ⅜ inch bead of adhesive is placed on a 2 inch by 2 inch piece of plywood. The adhesive on the plywood is contacted to the surface of a 3 inch by 3 inch piece of gypsum board. The boards of are pulled apart at time intervals after application of the adhesive (i.e., every 5 minutes) to check transference of adhesive from the plywood to the gypsum board. Transference is measured as the area of adhesive transferred from one board to the other. The open time is the minimum time required to transfer about 60% of the adhesive from the plywood to the gypsum board.
In another aspect, the invention features a water-based adhesive including between 39 and 48 weight percent of a polyvinyl acetate emulsion, between 9 and 12 weight percent of a plasticizer, between 39 and 47 weight percent of a particulate filler having a first distribution and a second distribution of particle sizes, and between 0.5 and 1.2 weight percent of mineral spirits.
In another aspect, the invention features a wallboard and wall frame assembly including a wallboard and a wall frame bonded together by an adhesive. At the time the wallboard and wall frame were bonded by the adhesive, the adhesive includes water, a binder, and a particulate filler and has a green strength sufficient to support a 4 foot by 8 foot wallboard on a wall frame without fasteners in the field of the wallboard within 15 minutes of applying the adhesive to the wallboard and wall frame.
The binder may be, for example, a polyvinyl acetate emulsion, such as an aqueous homopolymer emulsion of a polyvinyl alcohol protected colloid having a solids content of about 55 percent.
The particulate filler may include two distributions of particle sizes. The first distribution has particle sizes between about 3 and 6 microns in diameter, and the second distribution has particle sizes between about 14 and 21 microns in diameter. The particulate filler may be, for example, a relatively unreactive solid, such as calcium carbonate.
The adhesive may include a thickener, such as a modified cellulose or a polyacrylic acid.
The preferred adhesive has a viscosity between about 60,000 and 70,000 cps.
The adhesive may include a plasticizer, mineral spirits, or a dispersant.
In another aspect, the invention features a method of manufacturing a wallboard and wall frame assembly. The method includes the steps of: (a) providing a wall frame and a wallboard; (b) applying the water-based adhesive described previously to a surface of the wall frame; and (c) placing a wallboard on the adhesive applied to the surface of the wall frame to produce a wallboard and wall frame assembly.
In preferred embodiments, the wall frame is provided in a horizontal position and the applying and placing steps are carried out in the horizontal position. The method can include the step of raising the wallboard and wall frame assembly to a vertical position within 15 minutes of applying the adhesive to the wallboard and wall frame. The method can also include the step of inserting fasteners around the perimeter of the wallboard before raising the wallboard and wall frame assembly.
The adhesive can lead to a reduction in the number of fasteners used in constructing a wallboard and wall frame assembly. Importantly, it is possible to reduce, and preferably eliminate, the use of fasteners in the field of the wallboard while maintaining a high rate of production. By reducing the number of fasteners used in the field, the need for cosmetic alterations can be reduced. The wallboard and wall frame assemblies can be moved rapidly (i.e., immediately) after gluing. Further, the adhesive holds the assembly together well during movement of the assembly, minimizing the occurrence of wall pops.
Other advantages and features of the invention will be apparent from the detailed description, and from the claims.
DETAILED DESCRIPTION
The preferred adhesive includes a binder, a particulate filler, a thickener, and a plasticizer. The adhesive is a high viscosity, water-based adhesive that can be used in the fabrication of wallboard and wall frame assemblies in the manufactured housing industry (i.e., in-plant home building). The adhesive has good open time and green strength characteristics for these applications.
The open time of the adhesive depends on the composition of the adhesive as well as environmental conditions (i.e., humidity
Choi Steve
Stein Edward
Illinois Tool Works Inc.
Pitney Hardin Kipp & Szuch LLP
Rajguru U. K.
Seidleck James J.
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