Compositions for reduced food adhesion

Details Compositions for reduced food adhesion Compositions for reduced food adhesion

2000-06-21

2002-08-20

Woodward, Ana (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S157000, C524S159000, C524S230000, C524S231000, C524S313000, C524S315000, C524S318000, C524S413000, C524S432000, C524S436000, C524S445000, C524S449000, C524S456000, C524S606000, C524S609000, C524S611000, C525S180000

Reexamination Certificate

active

06437031

ABSTRACT:

FEDERALLY SPONSORED RESEARCH
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to compositions and methods for reducing food deposit adhesion to cookware. More specifically this invention relates to a resin composition having a glass transition temperature of at least 180° C. containing an amount of at least one fluorinated compound effective to reduce food deposit adhesion on cookware made from the composition. The resin composition may optionally contain at least one fatty acid ester, fatty acid amide, anionic surfactant, or a mixture containing at least one of the foregoing. The invention also relates to a method for providing plastic cookware having reduced food deposit adhesion.
2. Brief Description of the Related Art
Plastic cookware has gained increased acceptance and use in recent years due in part to their relatively low cost, durability with light weight, and flexibility in design. Unfortunately, adhesion of food deposits and the accompanying stains as observed with more traditional metal cookware is also obtained with plastic cookware. Non-stick cookware has been developed as a solution to adhesion of food deposits to reduce sticking and ease cleaning.
Methods to prepare non-stick cookware generally involve application of a surface treatment or lamination of a thin non-stick layer to the surface of the cookware. These methods are expensive and reduce the cycle time of the manufacturing process. What is needed in the art is a method for reducing the adhesion of food deposits on plastic cookware without secondary steps.
SUMMARY OF INVENTION
The method of the present invention to reduce adhesion of food deposits on cookware comprises a resin with a glass transition temperature of at least 180° C. and an amount of at least one fluorinated compound effective to reduce food deposit adhesion on cookware made from the composition. The resin composition may optionally contain at least one fatty acid ester, fatty acid amide, anionic surfactant, or a mixture containing at least one of the foregoing. The invention also includes the compositions and articles made from the compositions having reduced adhesion of food deposits. Various features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention, there is a method provided to reduce adhesion to food deposit on cookware made from at least one resin having a glass transition temperature of at least 180° C. The need for the high glass transition temperature is to allow for the high temperatures common during food preparation. Accordingly, the resins have to have sufficient heat resistance to resist deformation during use. Suitable resins include polycarbonates, polyimides, polyamides, polyamideimides, polysulfones, (such as polyarylsulfones, including polyphenylsulfones), polyethersulffones, polyetherketonet, polyetheretherketones, aromatic copolyesters, and polyetherimides as well as various blends containing at least one of the foregoing resins. These resins are generally known in the art as are methods for the preparation.
In one embodiment, the resin is a polyetherimide resin comprising structural units of the formula (1):
wherein the divalent T moiety bridges the 3,3′, 3,4′, 4,3′, or 4,4′ positions of the aryl rings of the respective aryl imide moieties of formula (I); T is —O—or a group of the formula —O—Z—O—; Z is a divalent radical selected from the group consisting of formulae (II):
wherein X is a member selected from the group consisting of divalent radicals of the formulae (D):
wherein y is an integer from 1 to about 5, and q is 0 or 1; R is a divalent organic radical selected from the group consisting of: (a) aromatic hydrocarbon radicals having from 6 to about 20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals having from 2 to about 20 carbon atoms, (c) cycloalkylene radicals having from 3 to about 20 carbon atoms, and (d) divalent radicals of the formula (IV):
where Q is a member selected from the group consisting of formulae (V):
where y′ is an integer from about 1 to about 5. A particularly preferred polyetherimide resin is the reaction product formed by melt polymerization of 2,2-bis [4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with one or more of paraphenylene diamine and metaphenylene diamine. The resins are commercially available from GE Plastics under the mark ULTEM resins.
Other particularly useful resins include polysulfones having repeating units of the formulae (VI), (VI), (VIII), (IX), and (X):
These materials are commercially available from BASF, Amoco, and ICI under a variety of tradenames.
Other particularly useful resins include polyamideimides of the formulae (XI), (XII), and (XIII) wherein n is an integer greater than about 20, preferably greater than about 50:
Typical commercially available polyarnideimides are sold under the trademark TORLON by Amoco Performance Products.
Other particularly useful resins include polyetherketones of the formulae (XIV), (XV), and (XVI) wherein n is an integer greater than about 20, preferably greater than about 50:
Typical commercially available polyetherketones are sold under the trademarks VICTREX and ULTRAPEK by BASF.
A second key component of the present invention is an amount of at least one fluorinated compound. The fluorinated compound preferably includes at least one fluorinated polyolefin or fluorinated siloxane or fluorinated siloxane polymer. The fluorinated polyolefins generally have an essentially crystalline structure and preferably have a melting point in excess of about 120° C. The fluorinated polyolefins are preferably a polymer of one or more fluorinated monomers containing ethylenic unsaturation and optionally one or more other compounds containing ethylenic unsaturation. The fluorinated monomer may be a perfluorinated monoolefin, for example hexafluoropropylene or tetrafluoroethylene, or a partially fluorinated monoolefin which may contain other substituents, e.g., chlorine or perfluoroalkoxy, for example vinylidene fluoride, chlorotrifluoroethylene and perfluoroalkyl vinyl ethers in which the alkyl group contains up to six carbon atoms, e.g., perfluoro (methyl vinyl ether). The monoolefin is preferably a straight or branched chain compound having a terminal ethylenic double bond and containing less than six carbon atoms, especially two or three carbon atoms. When units derived from monomers other than fluorine-containing monomers are present, the amount thereof is preferably less than 30 mole %, generally less than 15 mole %. Such other monomers include, for example, olefins containing less than six carbon atoms and having a terminal ethylenic double bond, especially ethylene and propylene. Suitable fluorinated olefins include fluorinated polyethylenes comprising reporting unit of the structural formula (XVII):
wherein b is an integer in excess of 50 and Y
1
to Y
4
, which may be the same or different, are selected from the group consisting of hydrogen, chlorine, bromine and fluorine, with the proviso that at least one of Y
1
to Y
4
is fluorine. Preferred fluorinated polyethylenes for the purposes of the present invention include poly(vinyl fluoride), poly(vinylidene fluoride), polytrifluoroethylene, polychlorotrifluoroethylene, polybromotrifluoroethylene, polytetrafluoroethytene, and copolymers thereof. A particularly preferred fluorinated polyethylene is polytetrafluoroethylene. Other suitable fluorinated polyolefins include polyperfluoropropane, perfluorobutadiene and polyhexafluoropropylene.
More specifically, polytetrafluoroethylenes are fully fluorinated polyethylenes of the basic chemical formula (—CF
2
—CF
2
—)
n
that contains about 76% by weight fluorine. These polymers are highly crystalline and have a crystalline melting point of over 300° C. Commercial polytetrafluoroethylenes are available from E. I. duPont de Nemours & Co., Inc. under the tradename Teflon

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