Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-11-09
2003-09-23
Harlan, Robert (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S318430, C526S325000, C526S347100, C526S335000, C526S318200, C526S318300, C526S319000
Reexamination Certificate
active
06624274
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to polymer compositions useful in a wide variety of fields, including making elastomeric articles of manufacture. Particularly, compositions of the present invention are useful in crosslinkable films, coatings, adhesives, gaskets and the like. The compositions are particularly useful when there is a need to avoid using conventional cure systems, namely sulfur-based systems.
In general, many conventional polymer compositions used in films, coatings and adhesives utilize sulfur-based cure systems. Sulfur-based links are introduced during the crosslinking of the polymer composition. In addition to sulfur, accelerators such as amines, thiazoles, sulfonamides, dithiocarbonates and thiuram are utilized. It would be desirable to eliminate the use of sulfur-based crosslinking agents and accelerators which may generate nitrosamines and cause copper staining, allergies and sensitization to accelerator residues and potential contamination of the films, coatings and adhesives. The potential also exists for curing agents or curing agent residues that are not bound to the polymer chains to bloom to the surface of the polymer. In practice this is sometimes seen as sulfur blooming and is undesirable since it can lead to particulate contamination, a particular concern in controlled environments. Blooming from the cure system can also alter performance properties in applications such as gasketing where it can interfere with adhesion or sealing properties.
Several alternatives to conventional cure systems exist such as the incorporation of functionality into a polymer through the use of N-methylol acrylamide and derivatives. While these provide suitable performance in some applications, residues associated with these materials such as acryamide, formaldehyde, and other volatile organic compounds are undesirable in many applications.
Allergies and sensitization is particularly a problem in medical gloves made from polymer latex compositions. Latex gloves are preferred since they can be made light, thin, flexible, tight-fitting, and substantially impermeable to a variety of liquids and gases. It is often desirable that the gloves possess adequate physical properties such as tensile strength and elongation, and are comfortable to the wearer. It is also desirable that the gloves possess adequate aesthetic properties with respect to drape, softness, etc., provide a good barrier to microbial penetration, and be substantially odorless. A combination of high tensile strength and elongation combined with a low modulus is typically preferred.
Conventional latex gloves have typically been formed of natural rubber primarily due to their resiliency, softness, adequate physical properties, and good elastic recovery. Nonetheless, many wearers of such gloves are allergic to proteins found in natural rubber. These individuals often experience difficulty when wearing the gloves. As a result, there have been efforts to develop gloves made from synthetic materials which are comparable to the natural rubber gloves in terms of comfort and physical properties. One synthetic alternative focuses on using poly(vinylchloride) (PVC). PVC is typically plasticized in order to be pliable enough to use in glove applications. Gloves formed from PVC are undesirable in many respects. For example, the gloves do not possess a soft and rubbery feel. Furthermore, the plasticizer may migrate through the PVC and leach out when in contact with solvents. Also, it is believed that synthetic gloves formed from these plasticized vinyl materials may provide an insufficient barrier to microbes due to imperfections in the film. Additionally, these gloves tend to display inadequate elastic recovery (snap) properties and poor softness. Various other glove materials are disclosed in U.S. Pat. No. 5,014,362 to Tillotson, U.S. Pat. No. 5,910,533 to Ghosal et al., and U.S. Pat. No. 5,997,969 to Gardon.
There, however, continues to be a need for polymers that can be cured in the absence of sulfur and accelerators. Such polymers should have the desirable characteristics of the conventional polymers, maintain the desired aesthetic and physical properties (e.g., high tensile strength and elongation properties); and obviate the undesirable features of polymers, that occur when using conventional sulfur-based cure systems, namely blooming, copper staining, allergies and sensitization to accelerator residues, and potential contamination in articles of manufacture sensitive to sulfur or accelerator residues.
SUMMARY OF THE INVENTION
To these ends, and to other objects and advantages, the present invention provides a polymer composition capable of being cured or crosslinked in the absence or without the use of conventional sulfur and accelerator cure systems and/or accelerators. The polymer is formed from at least one olefinically unsaturated monomers, and includes a conjugated diene monomer. Such polymer includes additional functionality provided by a chelating monomer. A suitable chelating monomer is an acetoacetoxy functionalized monomer. Such a polymer can then be crosslinked with a polyvalent metal ion crosslinking agent without the use of sulfur-based curing agents and/or accelerators. One use of such a polymer is a film to form various elastomeric articles of manufacture such as gloves, condoms, finger cots, etc. Another use of such a polymer is as a binding agent in articles of manufacture such as gaskets.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The polymer composition is formed from olefinically unsaturated monomers wherein the polymer contains at least one conjugated diene monomer and additional functionality provided by a chelating monomer. Suitable conjugated diene monomers that may be used include, but are not limited to C
4
to C
9
dienes such as, for example, butadiene monomers such as 1,3-butadiene, 2-methyl-1,3-butadiene, and the like. Blends or copolymers of the diene monomers can also be used. A particularly preferred conjugated diene is 1,3-butadiene.
The polymer may also optionally include other olefinically unsaturated monomers. Suitable olefinically unsaturated monomers include &agr;,&bgr;-unsaturated carboxylic acids, their anhydrides, and their aliphatic alicyclic, aromatic and heteroaromatic (partial) ester or (partial) amides such that the carbon skeletons of the base alcohols and amines of the esters and amides contain from about 1 to 20 carbon atoms in their carbon skeletons. Other suitable olefinically unsaturated monomers include &agr;,&bgr;-unsaturated nitriles, vinyl aromatics, vinyl halides, and vinyl esters of aliphatic carboxylic acids having between about 2 and 20 carbon atoms, and vinyl ethers of aliphatic, alicyclic, aromatic, and heteroaromatic alcohols having from 1 to 18 carbon atoms.
Sutiable &agr;,&bgr;-unsaturated carboxylic acids include itaconic, maleic, fumaric, and preferably acrylic and methacrylic acid.
Suitable esters or amides include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethyl hexyl (meth)acrylate, glycidyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, &bgr;-carboxyethyl acrylate, monomethyl maleate, dimethyl maleate, monooctyl maleate, monomethyl itaconate, dimethyl itaconate, di(ethylene glycol) maleate, di(ethylene glycol) itaconate, 2-hydroxyethyl methyl fumarate, ethylene glycol di(meth)acrylate, hexamethylene glycol di(meth)acrylate, maleimide, 3-chloro-2-hydroxybutyl methacrylate, dimethylaminoethyl (meth)acrylate and
Dow Reichhold Specialty Latex LLC
Harlan Robert
Myers Bigel & Sibley Sajovec, PA
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