Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-06-11
2002-09-03
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S054300, C525S054400, C525S059000, C525S293000, C525S330300, C525S331900, C525S440030, C525S445000, C525S479000, C526S279000, C526S310000, C526S313000, C526S320000, C526S328000, C526S332000, C526S335000
Reexamination Certificate
active
06444757
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to useful polymers that are capped by trifunctional olefinic moieties that include at least one ester group, particularly benzylidenecyanoacetates.
It is well known to include toughening agents (also known as impact modifiers or flexibilizers) in polymeric compositions in order to provide improved impact and shatter resistance to, and decreases the brittleness of, the cured polymeric composition. For example, the use of elastomers in structural adhesives to improve low temperature properties, such as impact resistance, is well known. Toughening agents are also used in plastics such as polystyrene, poly(butylene terephthalate) and polyacetal and fibers such as aramid and nylon.
In particular, P.C.T. Publication WO 97/39074 discloses the use of at least one polymeric material which can act as a toughening agent in an acrylic adhesive such as polychloroprene, polymer-in-monomer syrup, chlorosulfonated polyethylene rubber, copolymers of butadiene and at least one monomer copolymerizable therewith, for example, styrene, acrylonitrile, methacrylonitrile (e.g. poly(butadiene-(meth)acrylonitrile or poly(butadiene-(meth)acrylonitrile-styrene) and mixtures thereof; as well as modified elastomeric polymeric materials, such as butadiene homopolymers and copolymers as noted above modified by copolymerization therewith of trace amounts of up to about 5 percent by weight of the elastomeric material of at least one functional monomer (such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, styrene, and methyl methacrylate to give, for example, methacrylate-terminated polybutadiene homopolymers and/or copolymers).
U.S. Pat. No. 4,769,419 (“the '419 patent”) discloses structural adhesive compositions for metal-metal bonding applications. The adhesives include as tougheners olefinic terminated liquid rubbers that are reacted with monoisocyanate compounds. The '419 patent further describes acrylic adhesives with olefinic monomer, olefinic urethane reaction product of an isocyanate-functional prepolymer and a hydroxy-functional monomer, phosphorus-containing compounds, an oxidizing agent and a free radical source.
U.S. Pat. No. 5,641,834 (“the '834 patent”) and U.S. Pat. No. 5,710,235, both incorporated herein by reference, disclose adhesives that include as tougheners an olefinic-terminated polyalkadiene that includes carboxy ester linking groups and at least one nascent secondary hydroxyl group that is capped with a monoisocyanate. The composition also includes a free radical-polymerizable monomer such as an olefinic monomer and, optionally, a second polymeric material. In a preferred embodiment the composition is an adhesive that also includes a phosphorus-containing compound and an ambient temperature-active redox catalyst.
The '834 patent and the '419 patent are examples of capping oligomers with (meth)acrylate groups. Such oligomers are susceptible to homopolymerization and, thus, require the presence of an inhibitor for shelf-life stability. These inhibitors increase expense, complication and cause discoloration. Air, which contains oxygen—a powerful inhibitor, is often used to stabilize such oligomers. The use of air has several disadvantages. First, it can react with some oligomeric backbones—especially polydienes that contain residual unsaturation. This can result in molecular weight increase, peroxide formation that leads to instability, and discoloration. Storage in bulk can be problematic, as it is difficult to introduce air into the center of a large container. The pumps, sparge tubes and venting needed to introduce air into a system add complication and expense. It would be useful to have easily-prepared capped reactive oligomers that are not capable of homopolymerization.
The use of crosslinkers in polymeric compositions also is well known. Crosslinkers can provide solvent resistance, heat resistance, dimensional stability and resistance to weathering. The most common crosslinker for styrenic compositions is divinyl benzene, although unsaturated polyesters and di-, tri- and poly(meth)acrylates are also effective. A crosslinker that cures styrenic compositions faster than known crosslinkers would be very useful.
SUMMARY OF THE INVENTION
According to the invention there is provided a polymer having at least one reactive terminal or pendant functional group that has been capped with a trifunctional olefinic compound. There also is provided a method for making a polymer that includes contacting a base polymer having at least one reactive terminal or pendant functional group with a trifunctional olefinic compound under conditions effective to react at least one of the terminal or pendant functional groups with the trifunctional olefinic compound.
The capped polymer according to the invention provides a low cost polymer that is reactive with common olefinic monomers such as styrenic monomers at an increased reaction rate compared to other capped polymers. The end group or moiety resulting from the capping agent is incapable of homopolymerization thus eliminating some of the complications caused by oxidation of the base polymer as well as the requirements for inhibitors. In addition, the capped polymer can be made under anaerobic conditions since an air inhibitor is not required. Curing of compositions that include the capped polymer of the invention can be done aerobically or anaerobically, but anaerobically is preferred. Moreover, the capped polymer of the invention is stable in the presence of benzoyl peroxide, a common oxidizing agent.
Trifunctional olefinic compounds that include only one ester group bonded to one of the unsaturated carbon atoms are especially useful for capping. Such single ester compounds allow for capping of substantially all the reactive groups of the base polymer without chain extension or the formation of molecules containing more than one base polymer residue. Such capping avoids the viscosity increase problem associated with chain extension of the base polymer thus allowing for the production of a low viscosity capped polymer.
The capped polymers described above are particularly suitable as crosslinking toughening agents in multi-components compositions such as adhesives, coatings and matrices for composites. As a toughening agent, the capped polymer provides improved impact and shatter resistance to, and decreases the brittleness of, the cured adhesive, coating or matrix material. One useful application is a reactive adhesive that also includes at least one curable component, preferably a free radical curable ethylenically unsaturated compound.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Unless otherwise indicated, description of components in chemical nomenclature refers to the components at the time of addition to any combination specified in the description, but does not necessarily preclude chemical interactions among the components of a mixture once mixed.
As used herein, the following terms have certain meanings.
“Pendant group” means a functional group that is pendant to a polymer backbone chain.
“Polymer” also includes lower molecular weight oligomers such as dimers, trimers and tetramers.
“Room temperature” means ambient workplace (manufacturing or assembly plant, laboratory, etc.) temperature range, typically 10-40° C., more typically 20-30° C. “Terminal group or position” means a functional group occupying the terminal position of a polymer backbone chain or the terminal position of a chain pendant to a polymer backbone chain.
The ester-containing trifunctional olefinic compounds include olefinic or ethylenic unsaturation and at least three functional groups that are each bonded directly to the unsaturated carbon atoms. As used in the context of “trifunctional”, “functional group” includes alkyl as well as the various functional groups conventionally referred to in the organic chemical art. One of the functional groups is an ester having the structure —COOR
1
(i.e., carboalkoxy or carboxylic ester). Preferably, the other functional groups are
Dearth Miles B.
Lord Corporation
Pezzuto Helen L.
LandOfFree
Trifunctional olefinic-capped polymers and compositions that... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Trifunctional olefinic-capped polymers and compositions that..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Trifunctional olefinic-capped polymers and compositions that... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2861569