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US 4,460,737 AGranted
Polyurethane joint sealing for building structures
AssigneeRPM, Inc.
InventorsRobert M. Evans, Thomas M. Leonard
Life of this patent
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AssigneeRPM, Inc.
InventorsRobert M. Evans, Thomas M. Leonard
Estimating the term…
A profound improvement in the properties and capabilities of elastomeric polyurethane joint sealing compositions is achieved by incorporating a fibrillated polyolefin of high surface area which is rendered compatible by combining it with effective stabilizing cofillers, such as titanium dioxide, calcium carbonate, carbon black, fibrous talc, serpentine, kaolin, or various other metal silicate fillers. Such cofillers are capable of improving compatibility and stabilizing the sealant mixture so that unacceptable sweat out or exudation of liquid is prevented and so that the outer surface of the applied sealant has an acceptable surface quality after curing. When 2 to 8 percent by weight of fibrillated polyolefin of macrofibrillar structure, preferably containing macrofibrils with diameters from 1 to 10 microns, is incorporated in a polyurethane joint sealant together with 8 to 30 percent of stabilizing cofillers, it becomes possible to provide revolutionary new joint sealants with remarkable properties, such as Boeing sag values of 0.1 and below for caulking compositions applied to extremely wide joints. These unique non-sag joint sealants can be compounded to form strong soft low-modulus elastomers ideally suited for vertical joints subject to extreme cyclical movement as is common in modern building construction.
In a non-sag elastomeric-type joint sealing composition containing a curable polyfunctional polyurethane prepolymer with terminal reactive groups and an average molecular weight of at least 1000 mixed with fillers and other compounding ingredients and having a PFER value of at least 2 and a Boeing sag value below one, said composition being curable at ambient temperatures from 10.degree. to 40.degree. C. to provide a strong elastomeric polyurethane sealant with an elongation in excess of 100 percent, the improvement wherein said composition incorporates 2 to 8 percent by weight of a fibrillated polyolefin with a surface area (BET) of at least 5 square meters per gram comprising macrofibrils having an average diameter below 20 microns and an average aspect ratio of at least 30 to 1;
A non-sag elastomeric-type caulking composition comprising 30 to 70 percent by weight of a polyurethane prepolymer having an average molecular weight of at least 1000 and a free NCO content of from about 1 to about 8 percent, up to 45 percent by weight of a viscous organic plasticizer compatible with said prepolymer, up to 2.5 percent by weight of an adhesion promoter, 2 to 8 percent by weight of a fibrillated polyolefin having a surface area (BET) of at least 5 square meters per gram and a macrofibrillar structure and consisting predominantly of macrofibrils with a diameter below 20 microns, and 8 to 30 percent by weight of a compatible stabilizing cofiller that prevents substantial exudation of liquid, the amounts of said fibrillated polyolefin and said cofiller being such that the mixed composition as applied has a Boeing sag value below 0.9 and a PFER value above 2.5 and when cured provides a strong soft low-modulus elastomeric sealant with an elongation in excess of 100 percent and a Shore A durometer hardness below 45.
A plasticized cured polyurethane joint sealant of high tensile strength for sealing joints subject to large variations in width, said cured sealant having an elongation of at least 150 percent and a Shore A durometer hardness of from about 20 to about 45 and being formed from a viscous composition comprising 30 to 60 percent by weight of a polyurethane polymer having an average molecular weight of at least 1000, 10 to 45 percent by weight of a viscous organic plasticizer, 2 to 8 percent by weight of a long-chain fibrillated polyolefin with a surface area of at least 5 square meters per gram having a macrofibrillar structure and consisting predominantly of macrofibrils with a diameter below 20 microns, and 8 to 30 percent by weight of a compatibilizing cofiller that prevents substantial exudation of liquid, the amounts of said fibrillated polyolefin and said cofiller being such that the composition as applied has a Boeing sag value below 0.9 and a PFER value above 2.5 and is essentially free of exuded liquid at the outer surface.
In a building structure having two rigid members spaced apart to form a narrow joint and having a non-sag elastomeric polyurethan caulking composition disposed between and adhered to said rigid members to close and seal said joint, said caulking composition comprising 30 to 70 percent by weight of a polyurethane prepolymer with a free NCO content of 1.5 to 8 percent, up to 45 percent by weight of a viscous plasticizer, and 10 to 30 percent by weight of filler and having an elongation of at least 100 percent, the improvement wherein said caulking composition contains 2 to 8 percent by weight of fibrillated polyolefin with a surface area (BET) of at least 5 square meters per gram comprising a major portion by weight of macrofibrils with a diameter of 1 to 10 microns and an average length up to 1 millimeter, and also contains 8 to 30 percent by weight of a compatible stabilizing cofiller that stabilizes the composition to prevent substantial sweat out and exudation of liquid.
Dependencies are inferred from the claim text.