Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2001-11-09
2004-12-07
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C525S403000, C525S452000
Reexamination Certificate
active
06828403
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an adhesive composition useful for bonding glass to a substrate and a method of bonding a window to a substrate using a silane functional adhesive composition which is capable of being used without the need for a primer.
Polyurethane sealant compositions typically are used for bonding non-porous substrates, such as glass, to nonporous substrates, these are described in U.S. Pat. No. 4,374,237 and U.S. Pat. No. 4,687,533, both incorporated herein by reference. U.S. Pat. No. 4,374,237 describes a polyurethane sealant containing urethane prepolymers which have been further reacted with secondary amine compounds containing two silane groups. U.S. Pat. No. 4,687,533 describes a polyurethane sealant containing urethane prepolymers which contain silane groups which have been prepared by reacting a polyisocyanate having at least three isocyanate groups with less than an equivalent amount of an alkoxysilane having a terminal group containing active hydrogen atoms reactive with isocyanate groups to form an isocyanatosilane having at least two unreacted isocyanate groups. In a second step, the isocyanatosilane is mixed with additional polyisocyanate and the mixture is reacted with a polyol to form a polyurethane prepolymer having terminal isocyanato groups and pendant alkoxysilane groups. EP 856,569 discloses the use of polyoxyalkylene polymer terminated with silanes having hydrolyzable groups bonded thereto blended with apolyoxyalkylene polymer having no cross-linking groups can be used for to bond glass to metal. This adhesives have not been a commercial success.
However, when such sealants are used to bond glass substrates to painted substrates, such as for window installation in vehicle manufacturing, the lap shear strength of the bonded substrate may be less than desirable for safety or structural purposes. Consequently, a separate paint primer comprising a solution of one or more silanes is typically applied to a painted substrate prior to the application of the sealant in most vehicle assembly operations for bonding the windshield and the rear window. Further a separate primer is also applied to the ceramic frit coated on the edge of the window (glass primer). The use of primers in assembly operations is undesirable in that it introduces extra steps, additional cost, the risk of marring the paint surface if dripped on an undesired location and exposes the assembly line operators to additional chemicals. It would be desirable to provide a sealant which, when bonded to a painted substrate and glass then cured, provides a bond with a higher lap shear strength, particularly when used in the absence of a paint primer and/or a glass primer.
SUMMARY OF THE INVENTION
The invention is an adhesive composition comprising
a) i) a trialkoxysilane functional polyether or polyurethane wherein the polyether or polyurethane has a weight average molecular weight of 6000 or greater and a dialkyltin carboxylate or dialkyltin alcoholate; or
ii) a dialkoxysilane functional polyether or polyurethane and a dialkyltin alcoholate; and
b) a primary or secondary amino straight chain alkyl trialkoxysilane;
wherein the dialkyltin carboxylate or dialkyltin alcoholate is present in an effective amount to facilitate bonding of the adhesive to a substrate of from about 0.1 to about 1.0 percent by weight based on the weight of the adhesive and the primary or secondary amino straight chained alkyl trialkoxysilane is present in an amount which is effective to facilitate bonding of the adhesive to a substrate wherein the amount is from about 0.5 to about 1.5 percent by weight.
In another embodiment, the invention is a method of bonding a window in a vehicle. The process comprises applying to a window or a window frame of a structure an adhesive according to the invention; contacting the window with the window frame of a substrate wherein the adhesive is located between the window and the substrate; and allowing the adhesive to cure. This process is especially useful when the substrate is unprimed metal, plastic, fiberglass or a composite, optionally coated with a coating. In another embodiment it is useful when the window is unprimed.
The method of the invention allows the bonding of a window into a substrate without the need for priming the surface of the substrate and/or the surface of the window to which it is bonded. This is especially useful for bonding windows into automobiles.
DETAILED DESCRIPTION OF THE INVENTION
The adhesive composition of the invention contains a polymer having a flexible backbone and having silane moieties capable of silanol condensation. The polymer with a flexible backbone can be any polymer with a flexible backbone which can be functionalized with a silane capable of silanol condensation. Among preferred polymer backbones are polyethers, polyurethanes, polyolefins and the like. Among more preferred polymer backbones are the polyethers and polyurethanes, with the most preferred being the polyethers.
Even more preferably the polymer is a polyether having silane moieties capable of silanol condensation. In one embodiment, the polymer useful in the invention is a polymer as disclosed in Yukimoto et al., U.S. Pat. No. 4,906,707; Iwakiri et al., U.S. Pat. No. 5,342,914; Yukimoto U.S. Pat. No. 5,063,270; Yukimoto et al. U.S. Pat. No. 5,011,900; Suzuki et al. U.S. Pat. No. 5,650,467, all incorporated herein by reference. More preferably such polymers are oxyalkylene polymers containing at least one reactive silicon group per molecule. The oxyalkylene polymer which can be used in the present invention includes polymers having a molecular chain represented by formula (1):
—(R—O)
n
— (1)
wherein R represents a divalent alkylene group having 2 to 4 carbon atoms, and preferably 2 to 3 carbon atoms; and n represents the number of repeating units. The oxyalkylene polymer may have a straight chain or a branched structure, or a mixed structure thereof. From the viewpoint of availability an oxyalkylene polymer having a repeating unit represented by formula (2) is preferred:
—CH(CH
3
)CH
2
O— (2)
The polymer may contain other monomer units but preferably comprises the monomer unit of formula (1) in a proportion of at least about 50 percent by weight, particularly about 80 percent by weight or more. Oxyalkylene polymers having a number average molecular weight (Mn) of about 3,000 or more are preferred. Those having a Mn of about 3,000 to about 50,000 are even more preferred, and about 3,000 to about 30,000, are most preferred. Preferably the ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is not higher than about 1.6, which indicates that the polymer has an extremely narrow molecular weight distribution (i.e., it is highly monodisperse). The Mw/Mn ratio is more preferably not higher than about 1.5, and most preferably not higher than about 1.4. While molecular weight distribution is measurable by various methods, it is generally measured by gel-permeation chromatography (GPC).
The terminology “reactive silicon group” or “reactive silane capable of silanol condensation” means a silicon-containing group in which a hydrolyzable group or a hydroxyl group is bonded to the silicon atom and which is cross-linkable through silanol condensation reaction. While not limited thereto, typical reactive silicon groups are represented by formula (3):
wherein R
1
and R
2
each represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a triorganosiloxy group represented by (R′)
3
SiO—, wherein each of the three R′ groups, which may be the same or different represents a monovalent hydrocarbon group having 1 to 20 carbon atoms; when there are two or more of each of the R
1
or R
2
groups, each of the R
1
and R
2
groups may be the same or different, and the R
1
can be the same or different from R
2
; X is independently in each occurrence a hydroxyl group or a hydrolyzable group; when there are two or mor
Hsieh Harry W.
Mahdi Syed Z.
Essex Specialty Products Inc.
Gorr Rachel
LandOfFree
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