Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2003-09-17
2004-11-16
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S205000, C526S078000, C526S079000, C526S080000, C526S123100, C526S219600, C526S319000, C526S303100, C526S329200, C526S307600, C526S307700, C526S317100
Reexamination Certificate
active
06818684
ABSTRACT:
The present invention relates generally to polymeric compositions comprising polar monomers and multivalent cations. More particularly, the present invention relates to monophasic compositions comprising polar monomers that exhibit improved physical properties through the addition of a multivalent cation prior to polymerization. This invention also relates to the use of these improved compositions as, for example, coatings, polishes, sealants, caulks, adhesives, and plastics additives.
Complexes which comprise salts of various metals added to emulsions or dispersions containing polar monomers are known in the art. The reference article Roma-Luciow et al., “Complexes of Poly(Acrylic Acid) with Some Divalent, Trivalent and Tetravalent Metal Ions”, E. Polymer J., 37 (2001), pp. 1741-45 (“Roma-Luciow”) discloses metal complexes of poly(acrylic acid) or PAA with various metal salts such as chromium, iron, aluminum, bismuth, vanadium, uranium, nickel, copper, zinc, cobalt, calcium, barium, cerium, lanthane, and neodynium. The complexes disclosed in Roma-Luciow may be used, inter alia, as precursors in the elaboration of ceramics. The Roma-Luciow article compared and categorized the speed of exchange of water and of the carboxyl ligand for complexes having different metal salts.
Multivalent cations are oftentimes added to polymers or copolymers polymerized from polar monomers to improve the physical or chemical properties of the composition. For example, multivalent cations may be added after the polymer or copolymer has been formed to modify various functional groups present on the polymer chain. In a polymer or copolymer containing methacrylic acid (“MAA”), the carboxylic acid may be fully or partially neutralized by the addition of a cation to form a salt. It is believed that the addition of a cation may form ionic bonds with the negatively charged oxygen ions within the polymer or copolymer. These ionic bonds may lead to crosslinking of the polymer or copolymer chains. In this regard, a salt formed with a divalent cation may foster an ionic “cross-link” between the two copolymer chains. The resulting polymeric composition may be stronger as a result of this ionic “cross-link”. However, the presence of too much cation within the system could destabilize the polymer latex. Further, ionic cross-links that are formed post-polymerization may require the diffusion of polymer chains to form the ionic cross-links. This requirement generates a kinetic barrier to the ionic cross-linking and, oftentimes, may result in the failure of the system to form the maximum number of allowable cross-links from the given amount of multivalent cations.
U.S. Pat. No. 5,149,745 issued to Owens et al. (“Owens”) discusses reacting a previously formed acid-functional polymer with a transitional metal compound at a temperature above the Tg of the polymer to produce a crosslinked polymer. Owens teaches that the transitional metal compound must be relatively insoluble in water to prevent the compound from producing excessively high amounts of multivalent cations in solution. High levels of multivalent cations can cause dispersions or emulsions of acid-containing polymer to coagulate out of the emulsion or aqueous dispersion due to the multivalent cation instability of the polymer.
Multivalent cations may also be added to alter the physical or chemical properties of a polymer composition by providing distinct, inorganic phases within the poylymeric material. U.S. Pat. No. 5,952,420 issued to Senkus et. al. (“Senkus”) discloses pressure-sensitive adhesive polyacrylate microparticulate composites that are obtained via suspension polymerization of an aqueous mixture that comprises an acrylic acid ester of a nontertiary alcohol, a polar monomer, a styrene sulfonate salt, and an amount of surfactant above the critical micelle concentration. Water insoluble, metal cations in the form of metal oxide salts are added to the aqueous mixtures as suspension stabilizer modifiers. The resultant composite formed in Senkus comprises distinct phases of inorganic materials such as activated carbon, silica gel or alumina granules bonded together with the pressure-sensitive adhesive microparticulate in the mass of inorganic material. These multi-phasic or nonhomogeneous polymer-inorganic composites may exhibit a greater water sensitivity, water whitening, and poor film appearance which may be disadvantageous for certain applications such as pressure sensitive adhesives. Moreover, the composites of Senkus may fail to obtain the maximum number of cross-links from the given amount of multivalent cations.
WO 01/36505 issued to Young et. al. (“Young”) also discloses the addition of a multivalent cation in the form of a water insoluble salt to modify the physical and chemical properties of the polymeric composites. Young discloses suspension polymerized composites comprised of ionomeric particulates that modify the polymer matrix that it is compatible with to form an organic particulate-filled adhesive. Like Senkus, the resultant polymer-inorganic composite is comprised of more than one phase and suffers from many of the same disadvantages.
The present invention provides a polymeric composition with improved physical properties without adding a multivalent cation after polymerization. Instead, the present invention uses a multivalent cation, preferably a water soluble cation, to form a complex in situ with a portion of the polar monomer prior to and/or during polymerization. Further, the present invention provides a polymeric composition with improved physical properties without the formation of multiple inorganic phases. It is thus surprising and unexpected that the physical properties of polymeric compositions having polar monomers may be improved through the addition of a soluble cation salt, typically a multivalent cation, prior to and/or during polymerization and the staged addition of the polar monomer. The staged addition of the polar monomer and the addition of the cation salt may create a polymer or polymer latex with a high degree of ionic cross-linking without compromising polymer or polymer latex stability. Moreover, the present invention avoids gellation and gritting problems that are oftentimes experienced with the addition of a multivalent cation.
The present invention is directed, in part, to improved polymer compositions and processes for preparing same. Specifically, in one embodiment, there is provided a process for preparing a polymer, wherein the process comprises: providing a reaction mixture comprising a portion of at least one polar monomer and at least one multivalent cation; adding a mixture comprising the remaining portion of the polar monomer to the reaction mixture; and polymerizing the monomer to form the polymer. In certain embodiments, the reaction mixture in the providing step comprises at least two molar equivalents or greater of the total amount of polar monomer with respect to one molar equivalent of multivalent cation.
In another embodiment of the present invention, there is provided a process for preparing a polymer, wherein the process comprises: providing a reaction mixture comprising at least one polar monomer, at least one multivalent cation, and optionally at least one ethylenically unsaturated monomer; providing a monomer mixture comprising at least one polar monomer and optionally at least one ethylenically unsaturated monomer; adding the monomer mixture to the reaction mixture; and polymerizing the monomer to form the polymer.
In a further embodiment of the present invention, there is provided a process for preparing a polymer, wherein the process comprises: providing a reaction mixture comprising at least one polar monomer, at least one multivalent cation, and optionally at least one ethylenically unsaturated monomer wherein the at least one multivalent cation is soluble within a solvent; providing a monomer mixture comprising at least one polar monomer; adding a portion of the monomer mixture to the reaction mixture to form a polymer seed; adding the remainder of the monomer mixture to the
Rohm and Haas Company
Zalukaeva Tatyana
LandOfFree
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