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
2000-12-01
2003-04-22
Cain, Edward J. (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, C501S148000, C501S146000, C501S145000
Reexamination Certificate
active
06552113
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a nanocomposite composition comprising a matrix polymer, preferably a polyamide, at least one amorphous oligomeric resin, and a layered clay material uniformly dispersed therein. This invention also relates to articles produced from the nanocomposite and processes for producing the nanocomposite.
BACKGROUND OF THE INVENTION
Polymer-clay composites have received much attention lately due to their potential to improve polymer properties, including gas barrier, heat deflection temperature, and modulus. It has been found that polymer-clay composites often exhibit rapid crystallization that has been attributed to nucleation of the polymer matrix by the clay. This characteristic can be an advantage for opaque, crystalline molded parts with improved heat resistance and modulus such as the nylon composites disclosed in U.S. Pat. Nos. 5,385,776 and 4,739,007 and PET composites discussed in Journal of Applied Polymer Science, Vol. 71 (1999), pg. 1139-1146. However, the rapid crystallization of polymer-clay composites hinder their use in applications in which rapid crystallization is not desired, including, but not limited to profile extrusion, extrusion blow molding, stretch blow molding, film extrusion, and blown film. The rapid crystallization of polymer-clay composites makes it difficult, if not impossible, to obtain clear parts and greatly reduces the available processing window.
U.S. Pat. No. 4,739,007 discloses composite materials comprising a polyamide matrix polymer and a well dispersed layered silicate material that has been treated with monomeric components of the polyamide, then subjected to subsequent polymerization, which imparts high mechanical strength and excellent high temperature properties. U.S. Pat. No. 4,889,885 discloses composite materials comprising mixing non-polyamide matrix polymers and a well dispersed silicate material that has been treated with a monomer and/or oligomer of a resin other than a polyamide resin, and a polymerization step of polymerizing said monomer and/or oligomer in the mixture formed in the mixing step.
U.S. Pat. No. 5,385,776 discloses composite materials comprising a Nylon-6 matrix and a minor amount of a layered silicate material that is incorporated during melt extrusion and imparts rapid nucleation of the polyamide into the gamma crystal structure thereby improving modulus and resistance to plasticization by water.
U.S. Pat. No. 4,810,734 discloses nylon composites comprising a layered silicate material that has been treated with certain organic ammonium compounds and incorporated by synthesis using a dispersing aid.
PCT application WO 93/04117 discloses composite materials comprising a polyamide matrix and a layered silicate material that has been modified with certain primary or secondary organic ammonium compounds incorporated during melt extrusion to impart improved modulus to the polymer composite.
Journal of Applied Polymer Science, Vol. 71 (1999), pg. 1139-1146, discloses the rapid crystallization of composite materials comprising a polyethylene terephthalate matrix and an undisclosed clay material.
PCT application WO 93/11190 discloses Nylon composites comprising a layered silicate material that has been treated with certain organic ammonium compounds then with certain silane compounds and incorporated by melt blending.
MXD6 is a commercially available, partially aromatic, semi-crystalline nylon resin prepared from adipic acid and meta-xylylene diamine, and is also available as a copolyamide having comonomers including isophthalic acid. MXD6 and its co-polyamides are preferred barrier materials for use in multilayer PET bottles due to their similar processing conditions and rheology to PET and due to their improved resistance to delamination from PET compared to EVOH. Although MXD6 crystallizes more rapidly than PET, its crystallization rate is just slow enough to permit the manufacture of multilayer bottles. Nevertheless, because the oxygen barrier of MXD6 is only 10-40 times the oxygen barrier of PET, further improvements in the gas barrier properties of MXD6 containing materials are desirable.
During this work it was found that MXD6-clay composites, for example, can significantly improve oxygen barrier and, therefore, provide multilayer bottles with improved barrier and/or permit the preparation of high-barrier multilayer bottles comprising thin layers of the barrier material, which reduces raw material cost and improves recyclability. However, it was also found that many MXD6-clay composites crystallize more rapidly than clay-free MXD6, which makes the preparation of bottles more difficult and sometimes impossible. For many MXD6 clay composites, it was found that as the clay loading and resulting gas barrier properties increase, the crystallization rate of the polymer becomes more rapid. It is, therefore, desirable to significantly improve the gas barrier properties of MXD6 using nanocomposite technology without increasing the crystallization rate compared to that of neat MXD6.
It is an objective of this invention to overcome the nucleating effect caused by the presence of clay platelet particles and to provide polymer-clay composites that have the benefits of the improved properties afforded by the incorporation of clay platelet particles, but remain readily processible for a wide variety of applications.
SUMMARY OF THE INVENTION
Surprisingly, we have found that when certain amorphous oligomeric resins are used to treat clays, the increase in the crystallization rate of the matrix polymer material is lessened, and in some instances reversed. Further, the use of amorphous oligomeric resins have been found to provide additional benefits, including improved processability in blow-molding applications, improved adhesion, improved recyclability, improved color, improved barrier, improved clarity, and/or their combinations.
Therefore, as embodied and broadly described herein, this invention, in one embodiment, relates to a polymer-clay nanocomposite comprising
(i) a matrix polymer,
(ii) an amorphous oligomer, and
(iii) a layered clay material.
In another embodiment, the invention relates to a polyamide-clay nanocomposite comprising:
(i) a high molecular weight matrix polyamide, and incorporated therein
(ii) a layered clay material, wherein the clay material is dispersed in a matrix polyamide-compatible amorphous oligomeric resin.
In another aspect, this invention relates to a process for preparing a polymer-clay nanocomposite comprising the steps of:
(a) melt mixing a layered clay material with a matrix polymer-compatible amorphous oligomeric resin, to form an oligomeric resin-clay composite; and
(b) mixing the oligomeric resin-clay composite with a high molecular weight matrix polymer to produce the polymer-clay nanocomposite material.
In yet another aspect, the invention relates to a process for preparing polymer-clay nanocomposite comprising melt mixing a layered clay material, an amorphous oligomeric resin, and a matrix polymer, to produce the polymer-clay nanocomposite 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
Bagrodia Shriram
Bernard Linda Gail
Connell Gary Wayne
Gilmer John Walker
Lan Tie
Cain Edward J.
Deveau Todd
Lee Katarzyna W.
Troutman Sanders LLP
University of South Carolina Research Foundation
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