Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-04-14
2001-10-23
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06306936
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a beverage bottle comprising a rigid thermoplastic monolayer, bilayer or multilayer container having in at least one layer an amount of a substituted or modified cyclodextrin that prevents the passage of a permeant, or the elution of a soluble material from the thermoplastic into the liquid container contents. The invention also relates to biaxially oriented thermoformed polyolefin or polyester thermoplastic beverage containers resistant to the movement or passage of a permeant into the beverage and resistant to the extraction or elution of beverage soluble materials from the polyester web into the beverage.
BACKGROUND OF THE INVENTION
Rigid, or semirigid, thermoplastic beverage containers have been known for many years. One example of such containers are high density polyethylene milk containers that have a capacity of a quart, a gallon or other common sizes. These containers typically comprise high density polyethylene. High density polyethylene is made from an ethylene stream using a Ziegler-Natta catalyst in either liquid phase or gas phase processes. Other vinyl polymers, can also be used in formulating these beverage containers including polymers made from such monomers including ethylene, propylene, butylene, butadiene, styrene and others. Such materials often contain small concentrations of residual monomers, contaminants in the olefin feed, catalyst residues and other contaminants. Such containers are typically blow molded using common thermoforming technology to shape a preform into a finished bottle or container.
Biaxially oriented blow molded thermoformed polyester beverage containers are disclosed in J. Agranoff (Ed) Modern Plastics, Encyclopedia, Vol. 16, No. 10A, P. (84) pp. 192-194. These beverage containers are typically made from a polyester material. Such polyesters are commonly made from a diol such as ethylene glycol, 1,4-butane diol, 1,4-cyclohexane diol and other diols copolymerized with an organic diacid compound or lower diester thereof such as terephthalic acid, 2,6-naphthalene dicarboxylic acid etc. The condensation/polymerization reaction occurs between the dicarboxylic acid, or a dimethyl ester thereof and the glycol material in a heat driven reaction that releases water or methanol as a reaction by-product leaving the high molecular weight polyester material. Typically, bulk polyester is injection blow molded over a steel-core rod or are formed into a preform containing the polyester. The preform is introduced into a blow molding machine wherein the polyester is heated and blown to an appropriate shape and volume for a beverage container the preform can be a single layer material, can be a bilayer or multilayer preform. Such preforms can form bilayer or multilayer bottles.
The thermoplastic polyester is a high molecular weight material, but can contain a large variety of relatively low molecular weight compound, substantially less than 500 grams per mole. These compounds can be extractable into beverage within the container. These beverage extractable materials typically comprise impurities in feed streams of the diol or diacid used in making the polyester. Further, the extractable materials can comprise degradation by-products of the polymerization reaction, the preform molding process or the thermoforming blow molding process. Further, the extractable materials can contain residual diester, diol or diacid materials including methanol, ethylene glycol, terephthalic acid, dimethyl terephthalic, 2,6-naphthalene dicarboxylic acid and esters or ethers thereof. Relatively low molecular weight oligomeric linear or cyclic diesters, triesters or higher esters made by reacting one mole of ethylene glycol with one mole of terephthalic acid may be present. These relatively low molecular oligomers can comprise two or more moles of diol combined with two or more moles of diacid. Schiono,
Journal of Polymer Science: Polymer Chemistry Edition
, Vol. 17, pp. 4123-4127 (1979), John Wiley & Sons, Inc. discusses the separation and identification of PET impurities comprising poly(ethylene terephthalate) oligomers by gel permeation chromatography. Bartl et al., “Supercritical Fluid Extraction and Chromatography for the Determination of oligomers and Poly(ethylene terephthalate) Films”,
Analytical Chemistry
, Vol. 63, No. 20, Oct. 15, 1991, pp. 2371-2377, discusses experimental supercritical fluid procedures for separation and identification of a lower oligomer impurity from polyethylene terephthalate films.
Beverages containing these soluble/extractables, when consumed by the public, can exhibit an off-taste, a changed taste or even, in some cases, reduced taste due to the presence of extractable compounds. The extractable compounds can add to or interfere with the perception of either the aroma note or flavor notes from the beverage material. Additionally, some substantial concern exists with respect to the toxicity or carcinogenicity of any organic material that can be extracted into beverages for human consumption.
The technology relating to compositions used in the manufacture of beverage containers is rich and varied. In large part, the technology is related to coated and uncoated polyolefin containers and to coated and uncoated polyester that reduce the permeability of gases such as carbon dioxide increasing shelf life. The art also relates to manufacturing methods and to bottle shape and bottom configuration. Deaf et al., U.S. Pat. No. 5,330,808 teach the addition of a fluoroelastomer to a polyolefin bottle to introduce a glossy surface onto the bottle. Visioli et al., U.S. Pat. No. 5,350,788 teach methods for reducing odors in recycled plastics. Visioli et al. disclose the use of nitrogen compounds including polyalkylenimine and polyethylenimine to act as odor scavengers in polyethylene materials containing a large proportion of recycled polymer.
Wyeth et al., U.S. Pat. No. 3,733,309 show a blow molding machine that forms a layer of polyester that is blown in a blow mold. Addleman, U.S. Pat. No. 4,127,633 teaches polyethylene terephthalate preforms which are heated and coated with a polyvinylidene chloride copolymer latex that forms a vapor or gas barrier. Halek et al., U.S. Pat. No. 4,223,128 teaches a process for preparing polyethylene terephthalate polymers useful in beverage containers. Bonnebat et al., U.S. Pat. No. 4,385,089 teaches a process for preparing biaxially oriented hollow thermoplastic shaped articles in bottles using a biaxial draw and blow molding technique. A preform is blow molded and then maintained in contact with hot walls of a mold to at least partially reduce internal residual stresses in the preform. The preform can be cooled and then blown to the proper size in a second blow molding operation. Gartland et al., U.S. Pat. No. 4,463,121 teaches a polyethylene terephthalate polyolefin alloy having increased impact resistance, high temperature, dimensional stability and improved mold release. Ryder, U.S. Pat. No. 4,473,515 teaches an improved injection blow molding apparatus and method. In the method, a parison or preform is formed on a cooled rod from hot thermoplastic material. The preform is cooled and then transformed to a blow molding position. The parison is then stretched, biaxally oriented, cooled and removed from the device. Nilsson, U.S. Pat. No. 4,381,277 teaches a method for manufacturing a thermoplastic container comprising a laminated thermoplastic film from a preform. The preform has a thermoplastic layer and a barrier layer which is sufficiently transformed from a preformed shape and formed to a container. Jakobsen et al., U.S. Pat. No. 4,374,878 teaches a tubular preform used to produce a container. The preform is converted into a bottle. Motill, U.S. Pat. No. 4,368,825; Howard Jr., U.S. Pat. No. 4,850,494; Chang, U.S. Pat. No. 4,342,398; Beck, U.S. Pat. No. 4,780,257; Krishnakumar et al., U.S. Pat. No. 4,334,627; Snyder et al., U.S. Pat. No. 4,318,489; and Krishnakumar et al., U.S. Pat. No. 4,108,324 each teach plastic containers or bottles having preferred shapes or se
Beaverson Neil J.
Wood Willard E.
Cellresin Technologies, LLC
Merchant & Gould P.C.
Szekely Peter
LandOfFree
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