Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
2003-06-11
2004-09-07
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyester
C528S295000, C528S296000, C528S302000, C528S308000, C528S308600, C525S437000, C525S444000, C524S009000, C524S013000, C524S014000, C524S015000, C524S035000, C524S047000, C524S081000, C524S424000, C524S425000, C524S442000, C524S445000, C428S221000, C428S384000
Reexamination Certificate
active
06787245
ABSTRACT:
BACKGROUND
The inadequate treatment of municipal solid waste being put into landfills and the increasing addition of nondegradable materials, including plastics, to municipal solid waste streams are combining to drastically reduce the number of landfills available and to increase the costs of municipal solid waste disposal. While recycling of reusable components of the waste stream is desirable in many instances, the costs of recycling and the infrastructure required to recycle materials is sometimes prohibitive. In addition, there are some products that do not easily fit into the framework of recycling. The composting of non-recyclable solid waste is a recognized and growing method to reduce solid waste volume for landfilling and/or making a useful product from the waste to improve the fertility of fields and gardens. One of the limitations to marketing such compost is the visible contamination by undegraded plastic, such as film or fiber fragments.
It is desirable to provide components that are useful in manufacturing disposable products and are degraded into less contaminating forms under the conditions typically existing in waste composting processes. Such conditions may include temperatures no higher than 70° C., and averaging in the 55-60° C. range, humid conditions as high as 100 percent relative humidity, and exposure times of weeks or months. It is further desirable to provide disposable components that will not only degrade aerobically/anaerobically in composting, but will continue to degrade in soil or landfill. As long as water is present, such components should break down into low molecular weight fragments that can be ultimately biodegraded by microorganisms completely into biogas, biomass, and/or liquid leachate, as do natural organic compositions such as wood.
Biodegradable materials for use in packaging are well known. Biodegradable films are also known. For example, U.S. Pat. No. 3,602,225 discloses the use of barrier films comprising plasticized, regenerated cellulose films. U.S. Pat. No. 3,952,347 discloses biodegradable films comprising a non-biodegradable matrix, such as poly(vinyl alcohol), and about 40 to 60 weight percent of a biodegradable materials, such as starch.
Sulfonated aliphatic-aromatic copolyesters, as the term is used herein, include polyesters derived from a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids and, in addition, incorporate a sulfonated monomer, such as a salt of 5-sulfoisophthalic acid. Aqueous dispersions of solvent soluble linear sulfonated aliphatic-aromatic copolyesters that incorporate from 0.1 to 10 mole percent of the sulfonated aromatic monomer are disclosed in U.S. Pat. No. 3,563,942. U.S. Pat. No. 3,634,541 discloses fiber-forming sulfonated aliphatic-aromatic copolyesters that include 0.1 to 10 mole percent of xylylene sulfonated salt monomers, and U.S. Pat. No. 3,779,993 discloses linear, water-dissipatable sulfonated aliphatic-aromatic copolyesters which incorporate 2 to 12.5 mole percent of a sulfonated monomer.
Known sulfonated aliphatic-aromatic copolyester compositions generally have greater than 1 mole percent, more typically, greater than 2 mole percent, of the sulfonate component. Such materials typically have been found to have thermal properties that are inadequate or less than desired for some applications. Sulfonated aliphatic-aromatic copolyester compositions having high temperature characteristics, such as a high crystalline melting point, a high glass,transition temperature, or both, would be advantageous for some enduses, such as in films, coatings, laminates, dual ovenable food trays and the like. For example, a higher level of crystallinity and crystallization rate can allow simplified production processes, such as a reduction of film blocking (sticking) during the formation of polymeric films and faster mold cycle times in the production of molded shaped articles.
SUMMARY OF THE INVENTION
The present invention provides sulfonated aliphatic-aromatic copolyesters having reduced levels of sulfonation as compared to known sulfonated aliphatic-aromatic copolyesters. The Sulfonated aliphatic-aromatic copolyesters disclosed herein include a glycol component that is primarily, and preferably substantially, ethylene glycol. The sulfonated aliphatic-aromatic copolyesters disclosed herein have physical properties that are advantageous or optimal for certain applications without the need for blending the copolyesters with other materials. In particular, the sulfonated aliphatic-aromatic copolyesters disclosed herein provide an enhanced level of crystallinity as compared to that of known sulfonated aliphatic-aromatic copolyesters.
One aspect of the present invention provides sulfonated aliphatic-aromatic copolyesters and processes for producing the copolyesters. The sulfonated aliphatic-aromatic copolyesters comprise an acid component, a glycol component, and 0 to about 5.0 mole percent of a polyfunctional branching agent based on 100 mole percent acid component. The acid component comprises about 97.95 to about 20.0 mole percent of an aromatic dicarboxylic acid component, from about 2.0 to about 79.95 mole percent of an aliphatic dicarboxylic acid component, and from about 0.05 to about 0.75 mole percent of a sulfonate component (mole percentages are based on 100 mole percent total acid component). The glycol component comprises about 100 to about 95.0 mole percent of ethylene glycol as a first glycol component and from 0 to about 5.0 mole percent of a second glycol component (mole percentages are based on 100 mole percent total glycol component). The polyfunctional branching agent comprises polyfunctional acids, glycols or mixtures thereof. In some embodiments, the copolyesters contain one or more fillers. In some embodiments, the sulfonated aliphatic-aromatic copolyesters are biodegradable.
A further aspect of the invention provides shaped articles produced from the sulfonated aliphatic-aromatic copolyesters of the present invention, and processes to produce the articles.
A further aspect of the invention provides films produced from the sulfonated aliphatic-aromatic copolyesters of the present invention. In some embodiments, the films are uniaxially oriented. In some embodiments, the films are biaxially oriented.
Another aspect of the invention provides methods for producing oriented films comprising sulfonated aliphatic-aromatic copolyesters of the present invention. In some embodiments the sulfonated aliphatic-aromatic copolyesters contain fillers. The films can be, for example, uniaxially oriented or biaixially oriented. In some embodiments, the films are used in packaging applications such as food wraps.
A further aspect of the invention provides articles comprising substrates having laminated thereon films of sulfonated aliphatic-aromatic copolyesters of the present invention. Suitable substrates include, for example, paper, paperboard, inorganic foams, organic foams, inorganic-organic foams. Another aspect of the invention provides processes for producing articles comprising substrates having the sulfonated aliphatic-aromatic copolyesters laminated thereon.
A further aspect of the invention includes substrates coated with sulfonated aliphatic-aromatic copolyesters of the present invention. In some embodiments the sulfonated aliphatic-aromatic copolyesters contain fillers. In some embodiments, coated substrates comprising the sulfonated aliphatic-aromatic copolyesters can be used in packaging, such as food packaging and other food service articles.
DETAILED DESCRIPTION
The present invention provides sulfonated aliphatic-aromatic copolyesters, and articles from the sulfonated aliphatic-aromatic copolyesters and processes to produce the copolyesters and the articles. Preferred articles made from the sulfonated aliphatic-aromatic copolyesters are in the form of films, coatings, and laminates. Films, coatings and laminates comprising the sulfonated aliphatic-aromatic copolyesters can be deposited onto substrates such as, for example, paper, paperboard, inorganic foams, organic foa
Acquah Samuel A.
E. I. du Pont de Nemours and Company
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