Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-03-23
2003-05-13
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S314000, C526S348000, C526S348100, C526S307500, C526S171000
Reexamination Certificate
active
06562922
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The present invention is directed to unique vicinal hydroxyl-functionalized hydrocarbon polymers and to films, coatings and articles useful in packaging applications containing said polymers.
2. Background of the Invention
Ethylene/vinyl alcohol (EVOH) copolymers are commonly available and have been used in packaging applications. These copolymers are conventionally formed by free radical copolymerization of ethylene and vinyl acetate followed by conversion of the acetate pendant groups to hydroxyl groups. The resultant EVOH copolymers contain vinyl alcohol units randomly distributed along the polymer chain; have hydroxyl groups (disregarding residual acetate groups) configured head-to-tail when part of adjacent (vinyl alcohol) monomeric units; and have a considerable number of short and long chain branches. Such copolymers have been used as gas (oxygen) barrier films or coatings due to their ability to exhibit low gas permeability. However, this property is susceptible to degradation in the presence of high humidity and, thus, gives reduced protection to the effects of oxygen when used with moist products, such as certain food products and the like.
Several references have disclosed the copolymerization of ethylene and carbon monoxide (See JP 08244180; JP 09235370; JP 08244158). The resultant polyketone is reduced to provide a polyalcohol having a structure in which a single hydroxyl group is pendent from every third carbon of the polymer chain. These polymers, with their highly regular structure, are taught to provide enhanced gas barrier properties.
JP 10204121 also teaches polymers containing a high content of hydroxyl groups. The initially formed vinyl acetate/vinylene carbonate copolymer is converted into hydroxyl group containing polymers by hydrolysis. The resultant copolymer, although taught to be useful as a barrier material, has the deficiencies of having residual acetate groups in the copolymer product, poor film processing characteristics, especially on a commercial scale, and poor compatibility with conventional film forming polymers, such as polyolefins and the like.
Packaging materials, whether in the form of a film (single or multi-layer), or structural design which may be flexible, semi-rigid, or rigid and which may be of a lidded or collapsible design (“Packaging Article”), serve not merely to contain the substance being packaged but, depending on the nature of the substance, to also prevent ingress of harmful substances from the environment or, alternately, egress of volatiles from within a packaging article.
Oxygen from the atmosphere has long been recognized as one of the more harmful substances for many packaged materials, especially foodstuffs. Thus, the teaching herein shall be mainly directed but not limited to Packaging Articles which have high oxygen barrier properties, especially in environments of high relative humidity. The barrier properties are due to having a vicinal dihydroxy-functionalized hydrocarbon polymer of the present invention as part of the Article's structure.
In packaging oxygen sensitive substances, such as foodstuffs, beverages, and pharmaceuticals (collectively “products”), oxygen contamination can be particularly troublesome. Care is generally taken to minimize the introduction or concentration of oxygen or to reduce the detrimental or undesirable effects of oxygen on the foodstuff, pharmaceutical or beverage.
Molecular oxygen (O
2
) can be reduced to a variety of intermediate species by the addition of one to four electrons; these species are superoxide, hydroxy radical, hydrogen peroxide, and water. O
2
and water are relatively unreactive. However, the three intermediate species are very reactive. Also, O
2
can be activated to single electron state oxygen (which can undergo subsequent reduction to the more reactive oxygen species) by irradiation, or by the presence of catalytic agents. These reactive oxygen species are free radical in nature, and the oxidative reactions in which they participate are, therefore, autocatalytic.
Carbon-carbon double bonds are particularly susceptible to reaction with the intermediate species. Such carbon-carbon bonds are often found in foods and beverages, pharmaceuticals, dyes, photochemicals, adhesives, rubbers and polymer precursors. Virtually any product which has complex organic constituents will contain such carbon-carbon double bonds or other oxygen reactive components, and hence are susceptible to undergoing oxidative reactions. Thus, if the oxidation products adversely affect the quality, performance, odor or flavor of the packaged product, then preventing oxygen ingress into a Packaging Article will greatly benefit the packaged products' storage life and usefulness.
A number of strategies exist to deal with oxygen which is contained within a Packaging Article's free void space. The most basic is to remove the oxygen by vacuum or by inert gas sparging or both. More recently, oxygen scavenger compositions have been added to polymeric gasket compositions used in certain elements of Packaging Articles (e.g., bottle caps and can closures) as well as in one or more layers of polymeric films used to form Packaging Articles. Such scavenger compositions address the need to remove oxygen from the interior of a closed Packaging Article by reacting or combining with the entrapped oxygen or with oxygen which may enter the Packaging Article during transportation or storage. Although these are methods and compositions which address the concerns with entrapped oxygen, they do not primarily address the problems associated with entry of oxygen and other contaminants into a Packaging Article from the exterior environment.
Glass and metals provide packaging materials which have extremely good barrier properties with respect to the ingress of substances from the exterior environment. However, these packaging materials are costly, provide Packaging Articles which are heavy, rigid in construction and, in the case of glass, are breakable.
Polymers have also been used extensively in packaging applications where they have many advantages over the use of glass or metal. The advantages are derived from the diversity of polymers themselves in their mechanical, thermal, chemical resistance and optical properties and from the diversity and adaptability of fabrication techniques which can be employed. Thus, flexible bags, semi-rigid and rigid containers as well as clinging and shrinkable films can be made into Packaging Articles which have walls of homogeneous, laminated, coextruded, thermoformed or coated structure.
Further, packaging materials and the articles may be formed of a single layer (one composition throughout its thickness) or as a multi-layer structure wherein different layers of the structure are present to provide a combination of desired properties. For example, one or both surface layers may be composed of polymer(s) having groups which provide heat sealing properties. Other layers may be formed of polymers having high tensile strength to impart tear resistance to the resultant film or article. Similarly, polymers or blends of polymers may be used in different layers of a multi-ply material to impart gas barrier properties, printability characteristics, strength, heat shrink properties, adhesion between other layers which otherwise have poor adhesion properties to each other, as well as other properties desired of the resultant Packaging Article.
It has been presently found that improved packaging materials can be formed by utilizing the subject polymers which have a hydrocarbon backbone chain (preferably one which is substantially devoid of side chains), have a sufficient carbon to hydroxyl group ratio and have vicinal dihydroxyl groups directly pendent from the polymer chain to provide desired properties of compatibility with other polymers, resistivity to the effects of moisture, processability to produce a film, thermoformable or coated high barrier product.
Thus, it is the object of the present invention to provide a novel polyme
Bansleben Donald Albert
Connor Eric Francis
Grubbs Robert Howard
Roberts William Peyton
Choi Ling-Siu
Cryovac Inc
Ruble Daniel
Troffkin Howard
Wu David W.
LandOfFree
Vicinal hydroxyl group containing copolymer and articles... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vicinal hydroxyl group containing copolymer and articles..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vicinal hydroxyl group containing copolymer and articles... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3089960