Stock material or miscellaneous articles – Light transmissive sheets – with gas space therebetween and...
Reexamination Certificate
1997-06-19
2002-03-12
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Light transmissive sheets, with gas space therebetween and...
C525S125000, C528S503000, C052S786130, C156S109000
Reexamination Certificate
active
06355317
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a one part thermoplastic moisture cure polyurethane composition and a method of using this composition. This composition has primerless adhesion to glass and metal and is particularly well suited for use in the window area as an insulating glass sealant.
BACKGROUND OF THE INVENTION
Insulating glass (IG) units commonly have two panels of glass separated by a spacer. The two panels of glass are placed parallel to each other and a longitudinal spacer sealed around the perimeter of the glass maintains the gap therein. While this is the simplest configuration, other embodiments exist such as those with two spacers and three panels of glass. The spacers generally contain a desiccant to adsorb residual moisture which may enter the airspace during the life of the unit. There are various types of spacers including hollow metal and nonmetal tubes, preformed roll type spacers, metal U-channels, and various organic and inorganic foams.
The preformed roll type spacer comes in two types. One type contains a desiccating agent, an organic sealant and a metal foil and foamed elastomer which functions as both a vapor barrier and a spacer. The second type contains a desiccating agent and a strip of metal which functions as a vapor barrier. The second type requires that a sealant later be used. These rolls are stored in airtight containers until use, and are then applied to the glass units by hand. The organic sealant is often a polyisobutylene-polyisoprene rubber based system. A description of the second type of a preformed roll spacer may be found in U.S. Pat. No. 4,431,691 to Greenlee issued Feb. 14, 1984 and in U.S. Pat. No. 4,831,799 to Glover et al. issued May 23, 1989.
The hollow tube type of spacer contains a desiccant inside the metal tube. The tube may either be in multiple pieces requiring connectors at each comer which requires relatively more assembly, or it may be a single bendable piece requiring only one connector. The type of spacer utilizing folding corner connections is described in U.S. Pat. Nos. 4,530,195 issued Jul. 23, 1985 and 4,628,582 issued Dec. 16, 1986 to Leopold.
A third commercially used spacer is the metal U-channel spacer which is bent to provide a spacer frame having continuous comers, thereby relieving some of the labor required for assembly of the IG unit. The continuous channel allows for application of a desiccated matrix using conventional application equipment. This system may be found in U.S. Pat. Nos. 5,503,884 issued Apr. 2, 1996, 5,509,984 issued Apr. 23, 1996 and 5,510,416 issued Apr. 23, 1996 to Meyer et al. A description of the metal U-channel spacer may be found in U.S. Pat. No. 5,313,761 to Leopold issued May 24, 1994. Using the hollow tube spacer, the U-channel metal spacer or the preformed roll spacer requires the application of a sealant to adhere the glass panels to the spacer. Various types of sealants are currently used in the manufacture of IG units including both curing and non-curing systems. Liquid polysulphides, polyurethanes and silicones represent curing systems which are commonly used, while polybutylene-polyisoprene copolymer rubber based hot melt sealants are commonly used non-curing systems.
Liquid polysulphides and polyurethanes are generally two component systems comprising a base and a curing agent which are then mixed just prior to application to the glass. Silicones may be one component as well as two component systems. Two component systems require a set mix ratio, two-part mixing equipment and a cure time of between ½ hour to 4 hours or longer before the IG units can be moved onto the next manufacturing stage. These slow cure times can decrease the efficiency in the manufacturing process and can lower profitability. Furthermore, unexpected delays in the production process can result in these systems curing in the application equipment resulting in down time for clean up.
The advantages to using curing systems are higher ultimate bond strengths, better creep resistance and less susceptibility to glass slippage. Creep resistance is especially important after installation when the windows are in the vertical position in a building. Glass slippage, also known as glass movement can occur during shipping of the IG units.
Non-curing hot melt systems set faster and can overcome the disadvantage of having a slow cure time, but hot melts are more susceptible to fluctuations in ambient temperatures and may soften with high temperatures or stiffen with cold, and do not develop as high of ultimate bond strengths in comparison to the curing systems.
The sealants may be applied either by hand gunning or by automated three sided extrusion. The curing type systems are generally applied using the hand gun method because either they do not set fast enough or are not thixotropic enough for the fully automated three sided extrusion type lines. Hot melt systems are generally extruded although they may be applied by the hand gun method as well. The automated extrusion lines are a more efficient method of production and can lower manufacturing costs dramatically.
Sealants may be used in either a single seal construction or in a dual seal construction of the IG units. Single seal construction involves the application of only one type of sealant to all three sides of the spacer. A hot melt sealant is most commonly used for this construction, and in particular the hot melts are generally based on copolymers of polyisobutylene and polyisoprene. Curing systems may be used but this requires that the IG units be removed from the production lines until the system has cured enough to hold the unit together without slippage.
Dual seal construction involves application of first a primary sealant, usually a polyisobutylene based hot melt, which is extruded on two sides of the spacer. The glass panels are then bonded to each side of the spacer, and the area behind the spacer and between the two glass panels is then filled in with a secondary sealant which is usually a curing system. This system is advantageous because a fast rate of set can be achieved by employing a hot melt system, thereby increasing manufacturing efficiency. The polyisobutylene provides an immediate moisture barrier whereas the curing system contributes higher strength to the finished IG unit. A silicone sealant may not be used in the single seal construction because of higher moisture vapor transmission rates allowing the passage of moisture which accumulates between the glass panels. However, although this may be a more effective means of production, it is still not as efficient as using a fully automated extrusion system.
It is known in the hot melt adhesive art to blend polyurethanes with modifiers such as various polymers and tackifiers. U.S. Pat. Nos. 4,775,719 issued Oct. 4, 1988, U.S. Pat. No. 4,808,255 issued Feb. 28, 1989 and U.S. Pat. No. 4,820,368 issued Apr. 11, 1989 to Markevka et al. teach one-part systems which combine the characteristics of hot melt adhesives and curing polyurethane adhesives by blending various polymers and tackifiers with various urethane prepolymers. These systems are extrudable at elevated temperatures and allow for sufficient green strength from the hot melt portion of the system to form an initial bond quickly, and the cured polyurethane portion allows for a final rigid structural bond that is more impervious to temperature fluctuations than a hot melt adhesive.
U.S. Pat. No. 4,775,719 teaches a one-part thermally stable hot melt pressure sensitive moisture cure polyurethane composition in which a polyurethane prepolymer, which is the reaction product of a polyether polyol and an isocyanate compound, is blended with an ethylene vinyl monomer copolymer and a tackifying resin. U.S. Pat. No. 4,808,255 teaches blending a polyurethane prepolymer with an ethylene vinyl monomer copolymer and a tackifying resin. This invention differs from that described above in that the polyurethane prepolymer in this case is the reaction product of a polyester polyol and an isocyanate component. The polyester polyol m
Jarocz Jacqueline J.
Reid Kevin J.
Spinks Anne E.
H. B. Fuller Licensing & Financing Inc.
Loney Donald J.
Su Bin
LandOfFree
Thermoplastic moisture cure polyurethanes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastic moisture cure polyurethanes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic moisture cure polyurethanes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2860171