Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
1999-11-04
2002-11-26
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S150000, C528S048000
Reexamination Certificate
active
06486090
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to complexes of initiators and complexing agents comprising at least one hydroxide, alkoxide, or mixtures thereof The complexes are useful in initiator systems for polymerization of monomers.
BACKGROUND OF THE INVENTION
Systems for initiating the polymerization of monomers to make compositions, such as adhesives, are known in the art. U.S. Pat. Nos. 5,106,928, 5,286,821, and 5,310,835 to Skoultchi et al., for example, describe two-part initiator systems for initiating the polymerization of acrylic monomers. The first part of these two-part systems typically includes a stable organoborane amine complex and the second part includes an activator. The activator liberates the organoborane compound by removing the amine group, thereby allowing the organoborane compound to initiate the polymerization process. Activators are also sometimes referred to as liberators or decomplexers.
Common complexes in such systems include complexes of an organoborane and an amine. While such complexes may be useful in many applications, certain problems may arise due to the use of amine complexing agents in such conventional complexes. For example, when the complexes contain a primary amine, adhesives prepared therefrom may be prone to discoloration, such as yellowing. Furthermore, when including reactive diluents, such as aziridine-functional materials described in PCT Publication No. WO 98/17,694, for example, in compositions containing the complexes, the diluents may prematurely react with protic amines (i.e., those amines in which a nitrogen atom is bonded to at least one hydrogen atom) in such complexes, prematurely decomplexing the organoborane initiator. This phenomenon may even be to such an extent as to prematurely initiate polymerization of monomers present with the complexes or to degrade efficacy of the initiators for polymerization of subsequently added monomers.
In light of these potential problems and the desire to provide alternative formulations, further complexes are desirable, particularly for use in initiator systems, such as those used for polymerization of adhesives useful for bonding low surface energy substrates.
Initiator systems of the invention comprise: a complexed initiator comprising at least one of a complex of a complexing agent comprising at least one hydroxide and an initiator and a complex of a complexing agent comprising at least one alkoxide and an initiator; and a decomplexer. Preferably, the initiator comprises an organoborane initiator.
Complexes of organoborane initiators and complexing agents of the invention may be represented by the following general Formula (I):
wherein R
1
is an alkyl group having 1 to about 10 carbon atoms. R
2
and R
3
may be the same or different and are selected from (i.e., they are independently selected from) alkyl groups having 1 to about 10 carbon atoms and phenyl-containing groups. “Cx” represents a complexing agent of the invention. The value of “v” is selected so as to provide an effective ratio of oxygen atoms of the alkoxides and/or hydroxides to boron atoms in the complex.
The initiator systems are useful for initiating polymerization of at least one monomer. To initiate polymerization in such a manner, at least one monomer is provided and then blended with the initiator system. Polymerization of the at least one monomer can be initiated as such.
In one embodiment, the complexed initiator comprises a complexing agent represented by Formula (II):
(
(−)
O—R
4
)
n
M
(m+)
(II)
wherein each R
4
is independently selected from hydrogen or an organic group (e.g., an alkyl or alkylene group); M
(m+)
represents a countercation (comprising a monovalent cation, such as a Group IA metal (e.g., sodium and potassium) cation or onium, or a multivalent cation, such as a Group IIA metal (e.g., calcium and magnesium) cation); n is an integer greater than zero; and m is an integer greater than zero. Preferably, n and m are equal. Preferably, each R
4
is the same in a complexing agent. Particularly preferred complexing agents comprise those having a countercation comprising a cation selected from sodium, potassium, and tetraalkylammoniums.
According to another aspect of the invention, complexing agents of the invention are used as part of a kit. In one embodiment, kits of the invention comprise a polymerizable composition, wherein the polymerizable composition comprises:
at least one polymerizable monomer, and
at least one decomplexer; and
an initiator component, wherein the initiator component comprises:
a complexed initiator comprising at least one of:
a complex of a complexing agent comprising at least one hydroxide and an initiator, and
a complex of a complexing agent comprising at least one alkoxide and an initiator, and
an optional diluent.
A bonding composition can be prepared by mixing the polymerizable composition of the kit with the respective initiator component. The bonding composition can be used, for example, to prepare substrates at least partially coated with the bonding composition and bonded articles comprising a first substrate and a second substrate, with the polymerized bonding composition adhesively bonding the first and second substrates together. The bonding compositions are particularly useful for coating low surface energy substrates.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention provides initiator systems capable of initiating polymerization. More specifically, the invention provides “initiator systems” comprising (1) a complexed initiator (for example, an organoborane hydroxide, an organoborane alkoxide complex, or mixtures or combinations thereof) and (2) a decomplexer.
In one aspect of the invention, the initiator system is part of a multi-part kit. Such kits comprise at least a first part (i.e., a polymerizable composition) and a second part (i.e., an initiator component) for initiating polymerization of the polymerizable composition. Most preferably, for ease of use, the kits comprise only two parts. The two parts of the kit may be readily combined in a convenient, commercially useful, whole number mix ratio of 1:10 or less, more preferably 1:4, 1:3, 1:2 or 1:1, such that they can be easily used with multi-part dispensers. Such dispensers are shown in U.S. Pat. Nos. 4,538,920 and 5,082,147 and are available from ConProTec, Inc. (Salem, N.H.) under the trade designation, MIXPAC. The parts of the kit can be readily mixed to form bonding compositions, which readily polymerize to polymers, for example, adhesives.
The “polymerizable composition” typically comprises at least one decomplexer and at least one polymerizable monomer.
The “initiator component” typically comprises at least one complexed initiator (e.g., an organoborane hydroxide complex, an organoborane alkoxide complex, or mixtures or combinations thereof) and an optional diluent. When mixed with the polymerizable composition, the decomplexer in the polymerizable composition liberates the initiator (e.g., organoborane) from the complexing agent (e.g., a complexing agent comprising at least one hydroxide, alkoxide, or mixtures thereof), enabling polymerization of the monomer(s) to be initiated. “Bonding compositions” are those compositions resulting from mixing of the polymerizable composition and the initiator component according to one aspect of the invention. The bonding compositions are useful for bonding a wide variety of substrates, including substrates derived from polymers, wood, ceramics, concrete, and metals. The bonding compositions are especially useful for bonding low-surface energy substrates.
“Low surface energy substrates” are those that have a surface energy of less than 45 mJ/m
2
, more typically less than 40 mJ/m
2
or less than 35 mJ/m
2
. Included among such materials are, for example, polyethylene and polypropylene.
Other polymers of higher surface energy that may also be usefully bonded with the compositions of the invention include polycarbonate and polymethylmethacrylate. However, the invention is not so limited; t
3M Innovative Properties Company
Bell Mark L.
Pasterczyk J.
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