Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1998-06-08
2001-01-09
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S076000, C428S354000, C428S097000, C427S210000, C427S261000
Reexamination Certificate
active
06171683
ABSTRACT:
BACKGROUND
This invention relates to sheet materials with adhesives used in making, for example, covered foam products.
Automobile seat cushions and other foam products are typically produced by a foam-in-place process in which the seat cushion is chemically foamed against a finish fabric covering the seat. The process often begins by first laminating a lubricant-free urethane barrier layer to the finish fabric by, for example, flame lamination. A thin layer of foam placed between the fabric and the barrier layer acts as an adhesive to bond the fabric to the barrier. The resulting tri-layer fabric/foam/barrier composite is then cut and sewn into a sock cushion.
When the finished seat is sewn together from several different pieces of finish fabric, the seams of the sock cushion are sealed prior to foaming to prevent liquid components in the foaming process from bleeding through the finish fabrics and to assure a good vacuum barrier during the process of molding the foam cushion.
For ease of handling in cutting and sewing the composite, a slip sheet may be bonded to a surface of the barrier. For example, a polyethylene sheet may be heat bonded to the barrier to provide a slippery surface that prevents the composite from catching under the presser foot of a sewing machine.
SUMMARY
In one general aspect, a sheet material may be prepared and stored by applying an adhesive to one side of a first sheet, applying a second sheet to the adhesive to form a trilaminate, placing the trilaminate into a container that is substantially free of moisture, and sealing the container so that the trilaminate can be stored in an atmosphere substantially free of moisture. The adhesive is a cross-linking polymer that reacts with moisture to form cross-linked bonds.
Embodiments may include one or more of the following features. For example, the adhesive may include an isocyanate terminated oligomer and may soften in a temperature range between 60 and 72° Celsius. The cross-linked adhesive also may form a strong chemical bond that is heat resistant and will withstand temperatures greater than 100° Celsius and relative humidities of approximately 95%.
The adhesive may be heated to approximately 125° Celsius in a hot melt premelter prior to applying the adhesive to a roller. The adhesive may be applied to the first sheet from the roller by pressing the roller against the first sheet. The adhesive may form a continuous layer or may define discrete patterns, such as patterns resembling rows of pyramids.
The first sheet may include a polymer, such as polypropylene, that does not distort at temperatures of approximately 125° Celsius. Another property of the first sheet is that it may be peeled away from the solidified adhesive.
The second sheet may be nipped to the applied adhesive and may include a high molecular weight polyether-based thermoplastic urethane that is substantially free of moisture. The second sheet also may include an ethylene/vinylacetate copolymer, an ethylene acrylate copolymer, a metalocene-catalyzed olefin whose surface is treated for adhesion, an ionomer, or a film made using a resin having a relatively low softening or forming temperature and being free of lubricants or slip adhesives.
After the second sheet is nipped to the applied adhesive to form the trilaminate, the trilaminate may be passed over a cooling roll to cool the trilaminate and solidify the adhesive. After the trilaminate is placed in the container, dry air with a dew point below −10° Celsius may be used to purge the container.
In another general aspect, a sheet material includes a first polymer layer, a layer of adhesive bonded to the first polymer layer, and a second polymer layer covering the adhesive. The adhesive may include an isocyanate terminated oligomer.
In another general aspect, an article, such as a seat cushion, may be made by placing a barrier layer and a cover material in a shaped mold, creating foam by an exothermic reaction in a cavity defined by the barrier layer in the mold, and bonding the barrier layer to the cover material. The bonding is accomplished by using the reaction heat created in the exothermic reaction and the moisture in the ambient air and cover material.
Embodiments may include one or more of the preceding or following features. For example, prior to creating foam in the cavity, a vacuum may be applied to the mold to cause the barrier layer and cover material to conform in shape to the interior of the mold. The foam may be created by pouring chemicals into the mold, with the chemicals reacting to form the foam. The chemicals may include an isocyanate and a polyol mixture. After the foam sets, the cover material, barrier layer, and foam may be removed from the mold.
The cover material may be cut into pieces and sewn together to form a shell of the article, with the shell having an opening. The barrier layer may be formed by applying a cross-linking isocyanate terminated oligomer adhesive to one side of a sheet of polypropylene. A second sheet may be applied to the cross-linking adhesive to form a trilaminate. The second sheet may include a freshly-produced, high molecular weight polyether-based thermoplastic urethane. The trilaminate may be placed and stored in a container that is substantially free of moisture.
Other features and advantages of the invention will be apparent from the following description, including the drawings, and from the claims.
REFERENCES:
patent: 5286325 (1994-02-01), Miyota et al.
patent: 2122413 (1995-10-01), None
patent: 0 773 095 (1997-05-01), None
Dixon Merrick
Fish & Richardson PC
Omniflex
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