Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-11-24
2002-05-07
Gallagher, John J. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S331400, C428S419000, C528S058000
Reexamination Certificate
active
06383324
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved sealant for insulating glass windows which has a combination of the best properties of a polyurethane and a polysulfide. It further relates to a polyurethane sealant made from a hydroxyl terminated polysulfide polyformal.
The term “insulating glass window” refers to a structure comprising panes of glass, the faces of which are in spaced relationship, thereby providing a space between the panes which imparts insulating properties to the structure. In its most widely used form, 2 parallel panes are positioned in spaced relationship by metallic or organic resin spacers placed in board around the perimeter of the panes, thereby forming a U-shaped channel in which the interior faces of the pane are the legs and a side of the spacer is the base of the channel. Typically, the spacer is a hollow form filled with a water-absorbent material, such as a molecular sieve, to keep the enclosed air space dry. The U-shaped channel around the perimeter of the window is filled with a sealant which must have a combination of properties for satisfactory use. Some of those properties are as follows.
The sealant must have very low moisture vapor transmission (MVT) rate so that moisture is prevented from entering the dry space between the panes of glass. Moisture in such space tends to condense on the interior faces of the panes, creating visibility and aesthetic problems. If the sealant does not have a satisfactory MVT rate, the longevity of the insulated unit will be severely reduced.
The sealant should have good elongation and flexibility so that it “gives” during contraction and expansion of the insulated glass structure caused by temperature changes, thus relieving glass stress.
The sealant should also form an excellent bond with glass which is not degraded over long periods of use when exposed to sunlight, moisture, and large temperature changes. Tensile adhesion strength is an important indicator of bond strength.
In U.S. Pat. No. 3,386,963, Santaniello discloses certain isocyanate terminated polysulfide pre-polymers that are curable with polyols to form sealants and adhesives. The pre-polymers are made from hydroxyl terminated polysulfides having the formula:
HO—R′SS(R″SS)
n
R′—OH
wherein R′ and R″ are the same bivalent aliphatic radical wherein the carbon chain may be interrupted by oxygen atoms and the molecular weight is from 500 to 9000. There is no teaching about the properties of polyurethanes having a polysulfide backbone when R′ is polymethylene.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a method for sealing insulating glass windows with rugged sealants that combine the excellent liquid polysulfide attributes of good resistance to solvents and wood preservatives, low argon migration, good resistance to free radical oxidation, and good workability with the polyurethane characteristics of low moisture vapor transmission (MVT), low water swell, good electrical resistance, and good adhesion to organic components of insulated glass windows.
It is another object of this invention to provide a sealant whose hardness is less than that of a polysulfide-based polyurethane sealant of the prior art having the same molecular weight and cross-link density.
It is a related object of this invention to provide an isocyanate-terminated polysulfide which may be used as an intermediate or precursor in the formation of the insulated glass sealant.
REFERENCES:
patent: 2469404 (1949-05-01), Patrick et al.
patent: 2518245 (1950-08-01), Morris et al.
patent: 2527378 (1950-10-01), Bertozzi et al.
patent: 2582605 (1952-01-01), Richter et al.
patent: 2728748 (1955-12-01), Davis
patent: 3141294 (1964-07-01), Lawrence et al.
patent: 3169119 (1965-02-01), Dankert et al.
patent: 3386963 (1968-06-01), Santaniello
patent: 3419533 (1968-12-01), Dieterich
patent: 3852149 (1974-12-01), Sitter et al.
patent: 3997614 (1976-12-01), Lenke et al.
patent: 4431691 (1984-02-01), Greenlee
patent: 2024944 (1971-02-01), None
patent: 2119550 (1971-11-01), None
Hanson Arlene C.
Hobbs Stephen J.
Potts Keith B.
Vietti David E.
Falk Stephen T.
Gallagher John J.
Morton International Inc.
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