Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2003-03-17
2004-10-05
Harlan, Robert D. (Department: 1713)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C525S332100, C526S171000, C526S348000, C526S280000, C526S281000, C526S335000, C428S420000, C427S508000
Reexamination Certificate
active
06800170
ABSTRACT:
FIELD OF THE DISCLOSURE
The disclosed embodiments relate to adhesive and coating compositions and adhesive- and coating-dispensing systems, particularly catalytically-reactive adhesives and coatings.
BACKGROUND
A continuing need exists for adhesives and coatings that have robust adhesion to a variety of different types of substrates. Adhesion to low-surface-tension substrates such as polypropylene, polyethylene, cured ethylene-propylene-diene terpolymer rubber (“EPDM”) or thermoplastic elastomers is particularly problematic. In order to be commercially viable, adhesives and coatings must have certain characteristics in addition to superior bonding strength. Paramount among these characteristics is ease of dispensing from conventional systems, adequate open time, and sufficient shelf life.
In addition, a particular need exists for environmentally acceptable adhesives and coatings that avoid the use of volatile organic solvents. It has thus far been relatively difficult to develop environmentally acceptable adhesives and coatings that perform at a level equal to traditional solvent-based adhesives and coatings. For example, one major problem associated with bonds formed from an aqueous adhesive or coating is the relative susceptibility of the bonds to high temperature fluids and corrosive materials. A further need exists for coatings or adhesives that can be applied with relatively few steps and minimal energy use.
Adhesives used to join large surface area substrates are even more challenging since the adhesive must be able to withstand the exceptionally high stresses and adverse environmental conditions placed on the adhesive joint. Such adhesives are commonly referred to as “structural” adhesives and typically are used to join together two structural members such as metal and plastic substrates in the fabrication, repair and reconstruction of automotive and truck vehicle bodies and component panels and parts such as doors, roofs and hoods.
Metathesis polymers are one class of polymers that have not been exploited commercially in the adhesive or coating fields. Metathesis polymerization of olefin monomers is generally known and typically yields polymers having an unsaturated linear backbone. The degree of unsaturation functionality of the repeat backbone unit of the polymer is the same as that of the monomer. For example, with a norbornene reactant, the resulting polymer should have a structure represented by:
Adhesives and coatings are briefly mentioned in a few disclosures pertaining to metathesis polymers.
For example, PCT Patent Application Publication No. WO 97/38036 describes a metathesizable composition that includes a mixture of a thermal carbene-free ruthenium catalyst and a thermal ruthenium carbene catalyst. The polymers resulting from the metathesis polymerization are said to be suitable “as adhesives for bonding substrates having low surface energies (for example Teflon, polyethylene, polypropylene).” The compositions disclosed in WO 97/38036 are also said to be useful as “thermally curable adhesives” and as protective coatings on substrates. However, there is no example of a specific adhesive or coating formulation.
The metathesizable component in the compositions of WO 97/38036 may be a cycloolefin. Various structural formulae for cycloolefins are disclosed that encompass hundreds, if not thousands, of possible cycloolefin compounds. Norbornene per se, norbornene derivatives and norbornadiene are included in the lengthy list of possible cycloolefins, but only norbornene derivatives and polycyclic norbornenes (e.g., dicyclopentadiene) are used in the exemplified embodiments. Similar to the cycloolefin disclosure, WO 97/38036 discloses various structural formulae for each of the catalysts that encompass a myriad number of specific catalyst compounds. One of the possible catalysts is Cl
2
[P(C
6
H
11
)
3
]
2
Ru(IV)═CH—C
6
H
5
and it is used in the examples of WO 97/38036 (identified as “catalyst B”). However, these examples all describe using catalyst B and a cycloolefin monomer to make a molded article. Moreover, in comparative examples with catalyst B alone (i.e., it is not mixed with a carbene-free ruthenium catalyst) the disclosed results indicate that the composition incompletely polymerized or produced a soft solid.
SUMMARY OF THE DISCLOSURE
The disclosed adhesive and coating compositions are tailored to have certain practical properties that are important for a commercial adhesive. For example, the compositions are sufficiently stable under normal ambient conditions so that they can be prepared and then stored for an extended period prior to their use. Common adhesive or coating dispensing systems can easily be used to dispense and apply the adhesive compositions to a substrate. The compositions are environmentally acceptable. Finally, the compositions display remarkable bonding or adhesion strength, particularly for low-surface-tension substrates such as polypropylene and polyethylene.
In particular, according to one embodiment there is disclosed an adhesive or coating composition prepared by mixing together at least one metathesizable material comprising a highly-reactive cycloolefin (e.g., a norbornadiene) and a metathesis catalyst. It has been found that a highly-reactive cycloolefin can provide exceptional adherence to a low-surface-tension substrate. The metathesis catalyst may be a metal carbene catalyst having a structure described below. It has also been found that metal carbene catalysts that include trialkylphosphine or imidazol-2-ylidene can provide especially effective adhesives or coatings. Also disclosed is a method for adhering together at least two substrates, or coating a substrate, with this composition.
According to additional embodiments, the adhesive or coating composition may include at least two different metathesizable materials. In one variant, a norbornadiene may be at least one of the metathesizable materials. In a second variant, a composition can be prepared by mixing together a cycloolefin monomer and a liquid metathesis oligomer or polymer.
According to certain embodiments, the adhesive or coating composition can be provided as a two-part reactive system. In other words, there may be a first composition or part and a second composition or part that are independently prepared and stored separately until time of use. When used, the first and second parts are mixed together and undergo a reaction to make an adhesive or coating that is then applied to a substrate. Typically, the two parts are mixed together shortly before applying the adhesive or coating to the substrate.
One particular embodiment of a two-part reactive system includes (a) a first part comprising at least one first metathesizable material, and (b) a second part comprising (i) at least one liquid metathesis oligomer or polymer and (ii) a metathesis catalyst. The second part may be prepared by mixing together a metathesis catalyst and at least one metathesizable monomer that forms a liquid metathesis oligomer or polymer in the presence of the metathesis catalyst. It has been found that liquid metathesis oligomers or polymers are superior carriers for the metathesis catalyst for reasons detailed below. Also disclosed are methods for adhering at least two substrates together, or coating a substrate, using such a two-part system.
There are also disclosed particular systems for dispensing the two-part adhesive or coating that includes a first container containing a first composition comprising at least one metathesizable material wherein the first composition has a viscosity of at least about 10 cP at 25° C., a second container containing a second composition comprising a metathesis catalyst wherein the second composition has a viscosity of at least about 10 cP at 25° C., means for displacing the first composition from the first container, means for displacing the second composition from the second container, and a member that includes (i) elements that mix together the first composition and the second composition to produce an adhesive or coating and (
Caster Kenneth C.
Kendall Jonathan L.
Dearth Miles B.
Harlan Robert D.
Lord Corporation
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