SEALING GASKET ASSEMBLY, METHOD OF MANUFACTURE, AND METHOD OF APPLICATION

Abstract: A sealing gasket assembly of layers of support or carrier sheets, adhesives, release papers, and microporous gasketing material wherein various layers are peeled off to expose the proper layers for placing and adhering the gasket to substrates to be gasketed and processes for their assembly and utilization.

Description: , , METHOD OF APPLICATION FIELD OF THE INVENTION The invention relates to composite sealing gaskets and to methods for applying gaskets or sealants to substrates. BACKGROUND OF THE INVENTION There are two commonly used methods of applying gaskets or sealants to substrates^ rigid drop-in-placean non-rigid form-in-place. There is a need to provide a sealant form between these two general methods that combines the sealing benefits of form-in-place materials with the handling advantages of drop-in-place materials and is useful for hand installation in an assembly operation or in the replacement part market, such as gaskets for hand insertion between automobile drive train parts and the like. Accurately placing a form-in-place gasket on a substrate when the shape of the gasket is complicated by many convolutions and apertures is sometimes difficult by hand and may be quite expensive to do by automated mechanical methods. One example of a gasket which has a sealing compound layer, a removable carrier paper, and a flexible film cover is that disclosed by Buecken. et al.. in U.S. Patent 3,759,962. Incompressible spacers are sandwiched in this gasket assembly to aid the gasket in withstanding surface pressure which can force the sealant out of the edges of the gasket assembly. Materials such as release papers, cover films, and adhesives of varying adhesion strength suitable for use in sealing gasket assemblies are exemplified in U.S. Patents 4,629,634, 2,532,011, 3,854,736 and 4,635,948. Robots have been used to sandwich the layers of gasket assemblies together and also to apply a strip of sealing gasketing directly to a substrate. Where the path for accurate lay-down of the strip of gasketing is complicated, the robot may become complicated and expensive to construct and to operate. Peeling off layers or carrier sheets in proper order from a gasket assembly^hen applying the remainder of the assembly to a substrate can further complicate proper installation of the gasket and increase the cost. Because of its chemical, biological inertness, and lubricity, polytetrafluoroethylene (PTFE) has found wide application as a packing material in the food, chemical, and pharmaceutical industry. In the 1970's a new form of PTFE became available which was unique in that it combined high porosity with high strength. The process for manufacturing this unique product is described in U.S. Patents 3,953,566, 4,187,390, 4,096,227 and 3,962,153. SUMMARY OF THE INVENTION The invention comprises a composite sealing gasket assembly including a microporous polymer sealing gasketing material layered on one side with high-adhesion adhesive with or without a polymer film carrier layer and a cover layer of release paper. On the other side of the microporous polymer gasketing layer is layered a low-adhesion adhesive for holding the gasket to a carrier sheet. The carrier sheet is used to aid the installation of the gasket to the substrate. The process for preparing the assembly and the process for applying the assembly to a substrate also constitute a part of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross-section of a preferred gasket assembly of the invention. Figure 2 describes schematically a process for preparing an assembly of the invention. Figure 3 depicts an assembly of the invention with appropriate layers peeled back from the assembly for proper attachment of the sealing gasket to surfaces of substrates to be gasketed. Figure 4 is a perspective cross-section showing an assembly peeled back to expose the gasketing lying on an adhesive layer. Figure 5 shows a cross-section of a gasket assembly of the invention. DETAILED DESCRIPTION OF THE INVENTION Referring now to the figures to describe in detail the invention, Figure 1 shows a cross-section of a preferred sealing gasketing assembly of the invention with microporous gasket 4 layered together with a high-adhesion adhesive adhering gasket 4 to release paper 1. On the opposite side of gasket 4 is a layer of low-adhesion adhesive 5. which is covered with a carrier sheet 6 to maintain the shape of the assembly and to prevent adherence to substrates prematurely before the gasket assembly is unpackaged from an outer wrapper, unrolled, or otherwise made ready for utilization of or application of the.gasket to a substrate intended to be gasketed. Release paper 1 also protects gasket 4 until it is ready to be placed between two substrates to be gasketed. Layer 4 is preferably the microporous polytetrafluoroethylene (PTFE) disclosed in U.S. Patents 3,953,566, 4,187,390, 4,096,227, and 3,962,153 and may comprise more than one layer, such as a PTFE film - elastomeric filled PTFE film sandwich. A method for preparing the sealing gasketing of the invention is diagrammed in Figure 2. A roll of microporous gasketing material 4 is coated with low-adhesion adhesive either in film form from a roll or alternatively sprayed onto the film in a solution in a solvent which coating is dried before the microporous gasket material is combined with a carrier sheet to protect the gasket and the adhesive surface until use of the gasket. Release paper is layered onto a polymer carrier film which is coated by a known method, such as film or solution coating, with a high-adhesion adhesive on each side. This layered construction is adhered to the clean gasket material surface of the previously described gasket low-adhesion adhesive-carrier sheet construction. The combined constructions, the assembly of the invention, may be divided into separate sealing gaskets and packaged for storage and sale. An alternative process may be a combination of layers 1, 2 ; 3_, and Z upon which layer 4_ may be laid out in a pattern by robot means to follow the contours of a predetermined gasket pattern with proper spacing of the gasket on the pattern of gasketing away from apertures and edges. Other variations in known layering techniques common in the composite polymer film art may be utilized where they provide a properly protected gasket which is easily utilizable to place a gasket properly and easily between two substrates to be gasketed with accurate placement and easy avoidance of error in the gasketing operation. Figure 3 describes a method for use of the gasket assembly to gasket two substrates 7 and j_. Release paper I is peeled away from the assembly which is then adhered with proper accurate positioning by hand on substrate 7, which may be an internal combustion engine cylinder head for instance. On the opposite side of the assembly, carrier sheet f> and its coating of low-adhesion adhesive 5 is pulled from the surface to leave a surface of gasket material 4 upon which substrate fi, a valve cover for instance in this case, is laid to provide easy accurate gasketing of substrates 7 and fi. Another illustration of the assembly of the invention is shown in Figure 4, in which the assembly has layers 1 and £ peeled back to expose gasketing material 4 laid out in a carefully positioned pattern on adhesive layer 2. Release paper 1 is adhered to carrier layer 1 by the layer of adhesive Z. Figure 5 describes an alternative embodiment of the assembly of the invention wherein an optional polymer film carrier layer is utilized to aid in applying layers of high-adhesion adhesive 2 to the microporous gasket 4. Adhesive 2 is protected by a release paper 1 on the outside. Suitable polymer film materials for layer 1 may include, for example, polyester or tissue paper, or the like. Useful high-adhesion adhesives 2. may include high shear-strength rubber based pressure sensitive adhesives or hot melt systems. Low-adhesion adhesives 1 which may be used include acrylic polymer pressure sensitive adhesives or other removable/repositionable adhesives. Useful microporous polymers for gasket material 4 include the microporous PTFE described in the U.S. Patents listed above, a mat of fibriHated PTFE fibers, and filled PTFE both stretched and unstretched, the filling material including such materials as carbon, glass fibers, chopped glass fibers, glass microballoons, dyes, and pigments. The above methods can be modified by those skilled in the art to include other methods of laying down layers, peeling layers, and other processes both hand and machine operated for applying adhesives to various layers and for bonding layers of plastic film, adhesive, and gasketing together.

Claims: WE CLAIM; 1. A composite sealing gasket assembly comprising: (a) a first layer of release paper adhered to; (b) a second layer of high-adhesion adhesive which is applied to; (c) a third layer of microporous polymer sealing gasketing material . 2. A composite sealing gasket assembly comprising: (a) a first layer of release paper adhered to; (b) a second layer of high-adhesion adhesive which is applied to; (c) a third layer of mic * >rous polymer sealing gasketing material, which is a ered on one side to said second layer adhesive and on the other side to; (d) a fourth layer of low-adhesion adhesive upon which is layered and adhered on the other side to; (e) a fifth assembly supportive carrier sheet layer. 3. An assembly of Claim 1 wherein said third layer comprises microporous polytetrafluoroethylene, a mat of fibriHated polytetrafluoroethylene fibers, stretched filled polytetrafluoroethylene, or unstretched filled polytetraf1uoroethylene. 4. An assembly of Claim 2 wherein said third layer comprises microporous polytetrafluoroethylene, a mat of fibriHated polytetrafluoroethylene fibers, stretched filled polytetrafluoroethylene, or unstretched filled polytetraf1uoroethylene. 5. A process for assembly the sealing gasket assembly of Claims 1 or 3. 6. A process for assembling the sealing gasket assembly of Claims 2 or 4. 7. A proc ,s for .reparing a se ' ing gasket assembly which comprises a first layer of reiease paper, a second layer of high-tack adhesive,and a third layer of microporous polymer sealing gasketing comprising the steps: (a) assembling and adhering together said layers one and two by known bonding processes for application of adhesives to release papers and layering said adhesive together with a release paper into a unit; (b) adhering the adhesive side of said unit of layers one and two to one side of said third layer of microporous polymer sealing gasketing material. 8. A process of Claim 7 wherein said third layer comprises microporous polytetraf1uoroethylene. 9. A process 'for preparing a sealing gasket assembly which comprises a first layer of release paper, a second layer of high-tack adhesive, a third layer of microporous polymer sealing gasketing, a fourth layer of low-tack adhesive, and a fifth layer of carrier sheet comprising the steps: (a) assembling and adhering together said layers one and two by known bonding processes for application of adhesives to release papers and layering said adhesive together with a release paper into a unit; (b) adhering the adhesive side of said unit of layers one and two to one side of said third layer of microporous polymer sealing gasketing material; and (c) adhering to the other side of said third layer the adhesive side of the unit of the fifth layer of low-tack adhesive pre-assembled onto the sixth layer of carrier sheet. 10. A process of Claim 9 wherein said third layer comprises microporous polytetraf1uoroethylene. 11. A sealing gasket assembly prepared by the process of Claim 7. 12. A sealing gasket assembly prepared by the process of Claim 9. 13. A process for applying to a substrate a sealing gasket assembly of a first layer of release paper, a second layer of high-adhesion adhesive, and a third layer of microporous polymer gasketing material comprising the steps of: (a) removing said first layer from said assembly; (b) applying said assembly to a first substrate to be gasketed by contacting said second layer of said assembly with said first substrate; and (c) contacting said third layer .of said -assembly with a second substrate, thereby providing a sealing gasket between said two substrates. 14. A process for applying to a substrate a sealing gasket assembly of a first layer of release paper, a second layer of high-adhesion adhesive, a third layer of microporous polymer gasketing material, a fourth layer of low-adhesion adhesive, and a fifth layer of carrier sheet comprising the steps of: (a) removing said first layer from said assembly; (b) applying said assembly to a first substrate to be gasketed by contacting said second layer of said assembly with said first substrate; (c) removing said fourth and fifth layers of said assembly; and (d) contacting said third layer of said assembly and its adhered first substrate with a second substrate, thereby providing a sealing gasket between said two substrates. 15. A composite sealing gasket assembly comprising: (a) a first layer of release paper adhered to; (b) a second layer of high-adhesion adhesive which is applied to; (c) a third layer of carrier film which carries and supports said second and said first layers; (d) a fourth layer of high-adhesion adhesive which is respectively bonded to said third layer; and (e) a fifth layer of microporous polymer sealing gasketing material . 16. A composite sealing gasket assembly comprising: (a) a first layer of release paper adhered to; (b) a second layer of high-adhesion adhesive which is applied to; (c) a third layer of c_ rier film which carries and supports said second and said first layers; (d) a fourth layer of high-adhesion adhesive which is respectively bonded to said third layer; (e) a fifth layer of microporous polymer sealing gasketing material, which is adhered on one side to said fourth layer adhesive and on the other side to; (f) a sixth layer of low-adhesion adhesive upon which is layered and adhered on the other side to; and (g) a seventh carrier sheet layer. 17. An assembly of Claim 15 wherein said fifth layer comprises microporous polytetrafluoroethylene, a mat of fibriHated polytetrafluoroethylene fibers, stretched filled polytetrafluoroethylene, or unstretched filled polytetraf1uoroethylene. 18. An assembly of Claim 16 wherein said fifth layer comprises microporous polytetrafluoroethylene, a mat of fibriHated polytetrafluoroethylene fibers, stretched filled polytetrafluoroethylene, or unstretched filled polytetrafluoroethylene. 19. A process for assembling the sealing gasket assembly of Claims 15 or 17. 20. A process for assembling the sealing gasket assembly of Claims 16 or 18. 21. A process for preparing a sealing gasket assembly which comprises a first layer of release paper, a second layer of high-tack adhesive, a third layer of carrier film, a fourth layer of high-tack adhesive, and a fifth layer of microporous polymer sealing gasketing comprising the steps: (a) assembling and adhering together said layers one through four by known bonding processes for application of adhesives to carrier films and release papers and layering said adhesive coated films together with a release paper into a unit; (b) adhering the adhesive side of said unit of layers one through four to one side of said fifth layer of microporous polymer sealing gasketing material. 22. A process of Claim 21 wherein said fifth layer comprises microporous polytetraf1uoroethylene. 23. A process for preparing a sealing gasket assembly which comprises a first layer of release paper, a second layer of high-tack adhesive, a third layer of carrier film, a fourth layer of high-tack adhesive, a fifth layer of microporous polymer sealing gasketing, a sixth layer of low-tack adhesive, and a seventh layer of release paper comprising the steps: (a) assembling and adhering together said layers one through four by known bonding processes for application of adhesives to carrier films and release papers and layering said adhesive coated films together with a release paper into a unit; (b) adhering the adhesive side of said unit of layers one through four to one side of said fifth layer of microporous polymer sealing gasketing material; and (c) adhering to the other side of said fifth layer the adhesive side of the unit of the sixth layer of low-tack adhesive pre-assembled onto the seventh layer of release sheet. 24. A process of Claim 23 wherein said fifth layer comprises microporous polytetrafluoroethylene. 25. A sealing gasket assembly prepared by the process of Claim 21 or 23. 26. A sealing gasket assembly prepared by the process of Claim 22 or 24. 27. A process for applying to a substrate a sealing gasket assembly of a first layer of release paper, a second layer of high-adhesion adhesive, a third layer of carrier film to carry and support said first and second layers, a fourth layer of high-adhesion adhesive, and a fifth layer of microporous polymer gasketing material comprising the steps of: (a) removing said first layer from said assembly; (b) applying said assembly to a first substrate to be gasketed by contacting said second layer of said assembly with said first substrate; and (c) contacting said fifth layer of said assembly with a second substrate, thereby providing a sealing gasket between said two substrates. 28. A process for applying to a substrate a sealing gasket assembly of a first layer of release paper, a second layer of high-adhesion adhesive, a third layer of carrier film to carry and support said first and second layers, a fourth layer of high-adhesion adhesive, a fifth layer of microporous polymer gasketing material, a sixth layer of low-adhesion adhesive, and a seventh layer of release sheet comprising the steps of: (a) removing said first layer from said assembly; (b) applying said assembly to a first substrate to be gasketed by contacting aid second layer of said assembly with said first substrate; (c) removing said sixth and seventh layers of said assembly; and (d) contacting said fifth layer of said assembly and its adhered first substrate with a second substrate, thereby providing a sealing gasket between said two substrates. 29. A process of Claim 27 or 28 wherein said fifth layer comprises microporous polytetrafluoroethylene. 30. A sealed pair of substrates prepared by the process of Claims 13, 14, 27, 28, or 29.

Inventors: BILAS JOHN E, JOHNSON MICHAEL E, BILAS, JOHN, E., JOHNSON, MICHAEL, E.
Applicants: GORE & ASS, W.L. GORE & ASSOCIATES, INC.
Application year: 1990
Main classification: B32B29
IPC codes: B32B5, B32B7, C09K3, D21H27, F16J15