Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-12-21
2004-07-06
Wyrozebski, Katarzyna (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S186000, C524S447000
Reexamination Certificate
active
06759464
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to nanocomposites comprised of a functionalized elastomeric polymer, including oligomers which are elastomeric, which contains a particulate dispersion therein of an intercalated, and at least partially exfoliated, swellable clay, such as for example montmorillonite clay. Said clay may be pre-intercalated and thereafter blended with, or intercalated and at least partially exfoliated in situ within, a functionalized elastomer in an aqueous medium, wherein said functionalized elastomer contains at least one functional group selected from acid, acid-salt, anhydride, and protonated amine-modified epoxy groups. The invention further relates to articles of manufacture, including industrial belts, and tires, having at least one component comprised of such nanocomposite where such component may be a coating thereon or other integral component. Such tire component may be, for example, a tire tread, tire sidewall and/or tire innerliner.
The practice of this invention is considered herein to be a significant departure from a past practice of preparing a nanocomposite of elastomer and intercalated clay where such preparation has relied upon polymerization of elastomer precursor(s) in the presence of a water-swellable clay.
BACKGROUND OF THE INVENTION
Nanocomposites of elastomer(s) and intercalated water swellable clay, including partially exfoliated clays, have been prepared, for example, by polymerizing elastomer precursor(s) in an aqueous medium in the presence of the water swellable clay and have been prepared by pre-intercalating a water swellable clay with a quaternary ammonium salt and blending the clay with an emulsion of elastomer particles.
This invention contemplates two aspects of preparing nanocomposites comprised of elastomer modified clays and a third aspect of utilizing such prepared nanocomposites for the preparation of articles of manufacture.
The first aspect of preparing nanocomposites as elastomer modified clays contemplates elastomer intercalating an organoclay of a 2:1 layered silicate which contains a quaternary ammonium salt surfactant by blending the organoclay with an aqueous dispersion of pre-formed functionalized diene-based elastomer particles. The functional groups of the functionalized diene-based elastomer particles are selected from acid, acid-salt and/or anhydride groups. Preferably, the quaternary ammonium surfactant on the organoclay contains hydroxyl groups.
The second aspect of preparing nanocomposites as elastomer modified clays contemplates intercalating a clay of a 2:1 layered silicate which contain exchangeable cations within its galleries, by blending the clay with an aqueous dispersion of functionalized diene-based elastomer particles. For this aspect of the invention, the clay is not pre-intercalated with a quaternary ammonium salt. The functional groups of said functionalized elastomer particles are protonated amine modified epoxy groups. The exchangeable cations within the galleries of the clay may be comprised of, for example, one or more of sodium, potassium, magnesium and/or calcium ions. The protonation of said amine modified epoxy groups is envisioned to result in elastomer bound protonated amines which carry a cationic charge (e.g. N
+
) which provides for an ion exchange between said functional elastomer particles and said cation within said galleries.
The third aspect of the invention contemplates a utilization of blends of elastomer-modified clays of the first and/or second aspects of the invention with additional rubber composition ingredients comprised of, for example, reinforcing fillers, processing aids and curatives as well as additional elastomers.
An advantageous practice of the first aspect of the invention is a contemplated enablement of the use of a pre-formed functionalized elastomer of a molecular weight which can be tailored to a desired range of values to thereby provide an enhanced comparability of the functionalized elastomer with the organoclay in an aqueous medium without the need of organic solvents for aqueous dispersability of pre-formed elastomers. The practice of the first aspect of the invention is considered herein to be novel and a departure from past practice, particularly for the use thereof in the preparation of articles of manufacture such as, for example tires and industrial products such as belts and hoses.
For the second aspect of the invention, a functionalized elastomer in an aqueous medium is used in which the functionalized elastomer contains a protonated (cationic) charged bound to the elastomer due to protonation of amine modified epoxy functional groups on the elastomer which is, in turn, relied upon to intercalate the clay by an ion exchange process.
An advantageous practice of the second aspect of the invention is a contemplated enablement of use of a pre-formed functionalized elastomer of a molecular weight which can be tailored to a desired range of values to thereby provide an enhanced compatibility of the functionalized elastomer with the clay in an aqueous medium without the need of organic solvents for aqueous dispensability of pre-formed elastomers.
An additional advantageous practice of the second aspect of the invention is a contemplated enablement of eliminating a need of pre ion exchanging the 2:1 layered silicate (clay) with a quaternary ammonium salt (prior to addition of the clay to the functionalized elastomer) to thereby enhance compatibility of the diene-based elastomer with the hydrophilic 2:1 layered clay by virtue of the ion exchange mechanism directly with the protonated amine modified epoxy groups of the functionalized elastomer without the need of organic solvents. Such practice is considered herein to be novel and a departure from past practice, particularly for the use thereof in the preparation of articles of manufacture such as, for example tires and industrial products such as belts and hoses.
Historically, nanocomposites are composed of an elastomer and dispersion therein of an intercalated and partially exfoliated water-swellable clay.
From an historical prospective, water swellable layered silicate clays themselves which have been pre-intercalated with a non-polymeric intercalate such as for example a quaternary ammonium salt, might be referred to as an “organoclay”. The water-swellable clay is comprised of a plurality of stacked platelets which contains cationically exchangeable ions in the galleries between the platelets. The clay is intercalated by an ion exchange phenomenon between such ions within the galleries and, for example a more bulky quaternary ammonium salt to cause the galleries to expand. Such quaternary ammonium salt may contain olephilic or organophilic groups.
It is considered herein, however, that the efficiency of such intercalation or exfoliation of the clay is often insufficient to significantly improve many of the physical properties of the associated elastomer.
Swellable clays for use in this invention may sometimes be referred to as 2:1 layered silicate or clay. The clay materials that are crystalline have layer structures or layer ribbon structures which is considered herein to be well known to those having skill in such art. In such clay terminology, the basic configuration of the layer-structure may be described in terms of planes, sheets, layers, interlayers and the unit structure which is also considered herein to be well known to those having skill in such art. A single plane of atoms or ions may by form the minimum unit. A sheet may be an articulated combination of planes, and a layer may be an articulated combination of sheets. Layers may be separated from one another by an interlayer or a gallery. The layer structure can be divided into two groups, namely a 2:1 layer type and a 1:1 layer type, based upon the population of the sheets within the layer.
The general clay terminology is described in “Developments in Sedimentology 31
”, Electron Micrographs of Clay Materials
, Elsevier Scientific Publishing Company, 1981. The clays referred to in this invention are clays that are rea
Ajbani Manoj
Geiser Joseph Frank
Parker Dane Kenton
The Goodyear Tire & Rubber Company
Wyrozebski Katarzyna
Young, Jr. Henry C.
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