Package making – Methods – Filling preformed receptacle and closing
Reexamination Certificate
1999-01-08
2001-10-02
Vo, Peter (Department: 3721)
Package making
Methods
Filling preformed receptacle and closing
C106S783000, C106S786000, C241S014000, C241S027000, C141S094000, C156S094000
Reexamination Certificate
active
06295794
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a composition for joint compound including recycled wallboard constituents and a method and system for making the same.
2. Description of the Related Art
Interior walls of commercial and residential dwellings, including manufactured housing, are typically made by mounting wallboard panels onto an existing stud structure with conventional fasteners such as nails or drywall screws. A pair of abutting panels often has an uneven seam which is filled with “joint compound,” a filler which dries and hardens. The hardened joint compound is typically sanded to create a smooth and aesthetically pleasing wall surface which completes the drywall process. Joint compounds can be classified into two basic formulations, i.e., “setting” and “drying.” The drying type of joint compound is often formulated as a ready-mixed joint compound, while the setting type is provided as a powder which typically requires the addition of water immediately prior to application.
The setting and drying types of joint compounds have varying characteristics. The drying type is often a combination based on limestone (CaCO
3
), gypsum (hemihydrate) (CaSO
4
*1/2H
2
O) and/or gypsum (dihydrate) (CaSO
4
*2H
2
O) while the setting type is often based on gypsum (hemihydrate) (CaSO
4
*1/2H
2
O). After application into and over a seam between a pair of adjacent wallboard panels, the drying type joint compound dries by contact with air via the ensuent evaporation of water while the setting type reacts chemically to harden within a predetermined time.
Manufacture of either type of joint compound is costly. The basic ingredients of joint compounds are expensive process. In addition, government regulations often require that various ingredients such as asbestos, mica and talc be added or removed from these formulations to increase their safety.
In construction today, about one and one half pounds of wallboard waste is generated per square foot of a constructed dwelling. In the case of manufactured housing, this number may increase to two or three pounds of wallboard waste per square foot. This waste is costly due to the cost of materials as well as the cost required to dispose of the waste wallboard.
The latter is a significant problem. After disposal, the wallboard may degrade under certain conditions to form dangerous by-products, such as hydrogen sulfide gas. In addition, the sheer volume of wallboard waste as well as the dangerous by-products formed during its degradation has led many municipal landfills to prohibit dumping of wallboard waste and to demand recycling programs.
SUMMARY OF THE INVENTION
The invention, therefore, relates to a joint compound composition which includes recycled wallboard constituents and a method and system for making the same. Waste wallboard is recycled according to the invention so as to obviate the need for its disposal in a landfill. In addition, because wallboard and joint compound share at least one common ingredient, the wallboard can be reconstituted into a joint compound formulation which, in turn, obviates the need to purchase the common ingredient.
In one respect, the invention relates to an improved joint compound formulation suitable for insertion into and over a seam between adjacent wallboard panels comprising a binder, a preservative, a rheological additive, a surfactant and a filler, wherein the improvement lies within the fact that at least a portion of the filler comprises a granular material reclaimed from waste wallboard panels.
The granular material can comprise gypsum reclaimed from waste wallboard panels. At least a portion of the filler can be present in an amount of about 40 to about 90 percent by weight. The granular material can further comprise trace elements of residual paper fiber. The binder preferably comprises a material selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, starch, glue, adhesive, casein, and protein, either alone or in combination. The binder can be present in an amount of about 1 to about 8 percent by weight. The preservative can be a material selected from the group consisting of an antifoaming agent, a biocide, and a fungicide, either alone or in combination. The preservative can be present in an amount of about 0.01 to about 1 percent by weight. The rheological additive can be a material selected from the group consisting of methylcellulose, hectorite clay, attapulgite clay combined with water, either alone or in combination. The rheological additive can be present in an amount of about 0.01 to 3 percent by weight. The surfactant can be a material selected from the group consisting of non-ionic, cationic or anionic surfactants. The remainder of the filler other than that reclaimed from waste wallboard panel can comprise a compound selected from the group consisting of virgin gypsum, lime, limestone, talc, mica, perlite, and wollastonite, either alone or in combination. The remainder of the filler other than that reclaimed from waste wallboard panel can be present in the amount of about 2 to about 10 percent by weight.
In another aspect, the invention relates to a method for producing a joint compound composition suitable for insertion into and over a seam between adjacent wallboard panels comprising the steps of reclaiming a filler constituent from waste wallboard panel, and mixing the filler constituent with at least one of a binder, preservative, a surfactant and a rheological additive.
The method can also further comprise any or all of the steps of separating a paper backing from the waste wallboard panel; baling the removed paper backing into a compressed package; reclaiming a filler constituent from waste wallboard panel which further comprises the steps of providing a metal detector; actuating the metal detector to sense residual metal components remaining in the waste wallboard panel; and alerting a user of the presence of metal components remaining in the waste wallboard panel; providing at least one secondary storage facility for intermediate storage of waste wallboard material prior to the step of mixing the waste wallboard with other ingredients; grinding the waste wallboard panel to a predetermined mesh size; providing a mill for grinding the waste wallboard to the predetermined mesh size; periodically purging the contents of the mill to reduce the concentration of any trace contaminants therein; collecting the ground particulate waste wallboard material from the mill in at least one secondary storage facility; providing a mixing unit for mixing the particulate waste wallboard material with at least one of the binder, preservative, surfactant and rheological additive; fluidly interconnecting the mixing unit with a supply of the binder, the preservative, surfactant and/or the rheological additive; metering a predetermined amount of the particular waste wallboard material the binder, the preservative surfactact and/or the rheological additive into the mixing unit; actuating the mixing unit to mix the contents of the mixing unit into a joint compound mixture; providing the mixing unit with at least one shaft having radially-extending blades thereon; providing an outlet port on the mixing unit; providing a packaging system downstream of the mixing unit; fluidly interconnecting the outlet port of the mixing unit to the packaging system; providing a pump intermediate the outlet port of the mixing unit and the packaging system for controlling the flow of the joint compound mixture from the mixing unit to the packaging system; providing a viscometer fluidly interconnected between the mixing unit and the packaging system for indicating the viscosity of the joint compound mixture; alerting a user when the viscosity of the joint compound mixture reaches a predetermined value; providing a thermometer fluidly interconnected between the mixing unit and the packaging system for indicating the temperature of the joint compound mixture; alerting a user when the temperature of the joint compound mixture reaches a predetermined value; wherein the
Everett Jason A.
Nordt Frank Juergen
Spring David E.
Whipple Duane L.
Huynh Louis K.
Rader, Fishman, Grauer & McGarry an Office of Rader, Fishman & G
Universal Forest Products, Inc.
Vo Peter
LandOfFree
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