Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-05-30
2003-07-01
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C428S034100, C428S035700, C428S333000, C428S338000, C428S339000, C501S148000, C523S210000, C523S216000, C524S442000, C524S445000, C524S446000, C524S447000, C524S449000, C524S606000, C524S607000
Reexamination Certificate
active
06586500
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to polymer-clay nanocomposites comprising a matrix polymer and a layered clay material having an improved level of extractable materials. The polymer-clay nanocomposites comprising the layered clay material may be processed under normal conditions while providing low haze and improved oxygen barrier properties. This invention further relates to articles produced from the polymer-clay nanocomposites and processes relating to the nanocomposites.
BACKGROUND OF THE INVENTION
Thermoplastic materials are being increasingly used in the packaging of beverages and perishable foods. Plastics are often the material of choice for food and beverage packaging because of their clarity, flexibility, toughness, gas barrier properties, lighter weight, processability and high gloss. Polymer nanocomposites comprising a layered clay material having platelet particles dispersed therein have the potential for improved properties, including increased gas barrier, heat deflection temperature, and modulus.
Nevertheless, platelet particles derived from layered clay materials dispersed in a polymer nanocomposite may also induce crystallization and void formation during melt processing operations, such as the stretching or orientation of films. This may lead to very high levels of haze, and/or degradation of the gas barrier properties of the films made from nanocomposite materials, which renders the nanocomposites less desirable for food packaging applications, for example. Similar phenomena observed during the use of prior art nanocomposite materials in stretch blow molding applications can even lead to void and hole formation in the polymer films, which generally minimizes the usefulness of these compositions in high barrier applications.
Certain salts of organic cations have been used in the prior art to intercalate and/or cation exchange the layered clay materials used to make the nanocomposites. It has been taught in the prior art to use excess quantities of the salts of the organic cations when intercalating the layered clay material to facilitate complete cation exchange in the layered clay material, and thereby facilitate dispersion of the clay into various carrier materials to provide the desired individual platelet particles. As a result, intercalated layered clay materials in the prior art may be contaminated with the salts of the organic cations used as starting materials to intercalate and/or ion-exchange the layered clay material. It would be beneficial for some applications to provide an intercalated layered clay material with improved levels of certain extractable materials, such as extractable salts of organic cations.
SUMMARY OF THE INVENTION
The present invention is generally related to polymer-clay nanocomposites. The nanocomposites and/or intercalated layered clay materials of this invention result in improved physical properties as a result of the incorporation therein of a layered clay material comprising platelet particles. The layered clay material may be treated or modified with an organic cation to form an organoclay. A reduced level of permeability of gases, such as oxygen and carbon dioxide, through the nanocomposite material, and improved transparency of the nanocomposite may be achieved by employing a layered clay material having a improved level of certain extractable materials, such as certain salts of organic cations that are used to prepare the layered clay material.
Additional advantages of the invention will be set forth in part in the detailed description, which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following detailed description of the invention and the examples provided therein. It is to be understood that this invention is not limited to the specific components, articles, processes and/or conditions described, as these may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. For example, reference to an “article,” “container” or “bottle” prepared from the nanocomposites and processes of this invention is intended to include a plurality of articles, containers or bottles.
Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
Whenever used in this specification, the terms set forth shall have the following meanings:
“Layered clay material,” “layered clay,” “layered material,” “clay material” or “clay” shall mean any organic or inorganic material or mixtures thereof, such as a smectite clay mineral, which is in the form of a plurality of adjacent, bound layers. The layered clay comprises platelet particles and is typically swellable.
“Platelets,” “platelet particles” or “particles” shall mean individual or aggregate unbound layers of the layered clay material. These layers may be in the form of individual platelet particles, ordered or disordered small aggregates of platelet particles (tactoids), and/or small aggregates of tactoids.
“Dispersion” or “dispersed” is a general term that refers to a variety of levels or degrees of separation of the platelet particles. The higher levels of dispersion include, but are not limited to “intercalated” and “exfoliated.”
“Intercalated” or “intercalate” shall mean a layered clay material that includes treated or organically modified layered clay material having an increase in the interlayer spacing between adjacent platelets particles and/or tactoids. The intercalate may also refer to an “organoclay.”
“Exfoliate” or “exfoliated” shall mean platelets dispersed mostly in an individual state throughout a carrier material, such as a matrix polymer. Typically, “exfoliated” is used to denote the highest degree of separation of platelet particles.
“Exfoliation” shall mean a process for forming an exfoliate from an intercalated or otherwise less dispersed state of separation.
“Nanocomposite” shall mean a polymer and/or copolymer having dispersed therein a plurality of individual platelets obtained from a layered clay material.
“Matrix polymer” shall mean a thermoplastic or thermosetting polymer in which the clay material is dispersed to form a nanocomposite.
A weight percent of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.
A residue of a chemical species, as used in the specification and concluding claims, refers to the moiety that is the resulting product of the chemical species in a particular reaction scheme or subsequent formulation or chemical product, regardless of whether the moiety is actually obtained from the chemical species. Thus, an ethylene glycol residue in a polyester refers to one or more —OCH2CH2O— repeat units in the polyester, regardless o
Bagrodia Shriram
Germinario Louis Thomas
Gilmer John Walker
Lan Tie
Psihogios Vasiliki
Haley Jacqueline
Niland Patrick D.
Troutman Sanders LLP
University of South Carolina Research Foundation
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