Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
2000-06-28
2002-09-24
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polycarbonate
C428S413000, C428S423100, C428S474400, C428S480000, C428S483000, C428S515000, C428S516000, C428S517000, C428S519000, C428S520000, C428S521000, C428S522000, C428S523000, C604S332000, C604S338000, C604S339000
Reexamination Certificate
active
06455161
ABSTRACT:
This invention relates to essentially amorphous, non-chlorinated polymeric films and to the use of such films as effective barriers to odors and organic molecules.
Multilayer structures, which are substantially impervious to gases and/or moisture, are well known in the medical and food packaging industries. Currently, poly(vinylidene chloride) (PVDC) is used as one of the materials of choice for the gas barrier component of barrier films. For ostomy applications (i.e., colostomy and ileostomy), a film of PVDC sandwiched between opposing layers of low density polyethylene (LDPE) is widely used, with PVDC functioning as the gas barrier, and LDPE as the structural and sealant layer. Also, polyvinyl chloride (PVC) or chlorinated polyethylene (CPE) blended with ethylene-vinyl acetate copolymer (EVA) can be used in the structural and sealant layer, or other layers, of such a structure.
However, disposal of these chlorine-containing materials presents a number of potential environmental concerns, especially relating to incineration of these materials after use in hospitals or otherwise. In addition, exposure to di-2-ethylhexyl-phthalate (DEHP), a common plasticizer utilized with PVDC and PVC, may present a number of health-related concerns, including reduced blood platelet efficacy, and potential links to liver cancer.
Non-chlorine containing polymeric resins, such as ethylene-vinyl alcohol copolymers (EVOH), are also used as barrier layers and have been suggested for ostomy applications. However, while the barrier properties of EVOH copolymers are very high under dry conditions, they rapidly deteriorate in the presence of moisture. Thus, EVOH copolymers are not desirable for ostomy applications.
U.S. Pat. Nos. 5,496,295, 5,658,625 and 5,643,375 describe multilayer barrier films and articles made thereof. These films are useful, among others, in ostomy applications, and comprise a gas barrier layer of a chlorine-free organic polymer, which is substantially impermeable to oxygen gas, and a moisture barrier layer of a mesophase propylene-based material. The chlorine-free organic polymer gas barrier layer includes vinyl alcohol polymers, such as EVOH copolymers, polyvinyl alcohol (PVOH), polyacrylonitrile, polystyrene, polyester and nylon either alone or blended with each other. The moisture barrier layer comprises a mesophase propylene polymer-based material, such as mesomorphous polypropylene, mesopolymer blends and/or mesocopolymers. Quenching a propylene-based material from the melt state forms the mesophase propylene-based material.
EP 0 700 777 Al describes a chlorine-free multilayer film useful for manufacturing bags or pouches for ostomy/urostomy applications and comprising a seven layer structure. This structure comprises a gas barrier layer of a chlorine-free organic polymer which is substantially impermeable to oxygen, such as one of the above vinyl alcohol polymers, polyamides, polyesters and polystyrenes; two tie layers each contacting one side of said barrier layer; an inner surface layer; an outer surface layer and two intermediate layers positioned between said surface layers and comprising an ethylene-propylene (EP) copolymer.
EP 0 418 836 A3 describes multilayer oriented films suitable for use in the food packaging industry and having layers of a propylene homopolymer or copolymer, a co-polyester layer and an adhesive layer of a polar-modified polyolefin located between, and bonded to, the propylene polymer and co-polyester layers.
EP 0 056 323 A1 describes a thermoformable laminate for a sterilizable packaging comprising a cast layer of polyester, including polybutylene terephthalate, glycol-modified polyethylene terephthalate (PET-G), and a copolymer of cyclohexane dimethanol and terephthalic acid, joined by a bonding layer consisting of polypropylene (PP), LDPE or an ionomer resin. However, since such structures are targeted for thermoformable packaging applications, they possess high modulus and, therefore, cannot provide the required level of quietness needed for ostomy bag application as a result of the relatively rigid polymers used for skins composition. Additionally, the Tangent Delta (Tan &Dgr;) value of the skin polymers (LDPE, crystalline PP and ionomer resins) of these laminates indicate that they do not provide a quiet film as described below.
EP 0 588 667 A2 describes a multilayer film useful in moisture barrier packaging applications having at least one layer comprising a blend of propylene polymer or copolymer and a hydrocarbon resin and two additional layers comprising a propylene homopolymer or copolymer, an ethylene-alpha-olefin (EAO) copolymer, an ionomer, polybutylene or blends thereof. A core layer of an EVOH copolymer or another oxygen barrier material or high density polyethylene (HDPE) can be included in some embodiments.
Attempts to find additional chlorine-free polymeric films suitable for use as barrier layers have been guided by a generally held belief that a polymer having good oxygen barrier properties would also exhibit good barrier properties to organic products and odors. (See, for example, “Plastic Film Technology, High Barrier Plastic Films for Packaging”, volume 1: The use of Barrier Polymers in Food and Beverage Packaging, M. Salame, pp. 132-145 (1989)). Therefore, attempts to find polymeric films with sufficient barrier properties for use in the medical and food-packaging industries have focused upon the oxygen permeability of a given polymeric film. However, the inventors of the present application have found that not all polymers having low oxygen permeability exhibit odor barrier properties sufficient for ostomy applications and vice versa.
Studies have shown that human feces contain more than 122 volatile compounds as analyzed by gas chromatography/mass spectrometry. (See “Identification of Specific Trace Levels of Chemicals in Human Feces”, Dmitriev M. T.,
Lab. Delo
(1985), (10), 608-14; “Gas-Chromatographic and Mass-Spectrometric Analysis of the Odour of Human Feces”, J. G. Moore,
Gastroenterology,
1987, 93, 1321-9; M. D. Levitt, “Only the Nose Knows”,
Gastroenterology,
1987, vol. 93, No. 6, 1437-8; “Influence of Nutritional Substrates on the Formation of Volatiles by the Fecal Flora”, M. Hiele,
Gastroenterology,
1991, 100, 1597-1602; “Screening Method for the Determination of Volatiles in Biomedical Samples”; Y. Ghoos,
Journal of Chromatography,
665, 1994, 333-345; and “Influence of Dietary Protein Supplements on the Formation of Bacterial Metabolites in the Colon”, B. Geypens, GUT, 1997, 41, 70-76.)
These studies indicate that compounds responsible for fecal odor are mainly indoles and sulfide derivatives. Thus, compounds having relatively small molecules, such as, for example, hydrogen sulfide (H
2
S) or methyl mercaptan (CH
3
SH), compounds having larger molecules, such as, for example, ethyl sulfide, dimethyl disulfide (DMDS) or diethyl disulfide (DEDS), and compounds having large molecules, such as, for example, dimethyl trisulfide, indole or 3-methyl indole, are responsible for fecal odor.
Therefore, there remain needs in the art for polymeric films which (a) are environmentally safe, (b) are hydrolytically stable, and (c) exhibit low permeability to both small and larger molecular diameter odor-causing molecules. Furthermore, depending upon the end-use of such films, there remains the need for these films to be quiet, i.e., having low noise emission when crumpled.
Those needs are met by the present invention. Thus, the present invention provides essentially amorphous, non-chlorinated (or chlorine-free) polymer films useful as barriers to odors and organic compounds, as well as methods of using such films as barriers to odors and organic molecules in a monolayer or a multilayer film structure.
A first embodiment of the present invention is an essentially amorphous, non-chlorinated polymer film, the film functioning as a barrier to at least one of odors and organic molecules that have a diameter of 0.40 nanometer (nm) or more (≧) with barrier functionality being determined by at least one of a) a 3-methy
Bonekamp Jeffrey E.
Regnier Francois J. F.
Tung Harvey C.
Woods Rochelle A.
Chen Vivian
Dow Global Technologies Inc.
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