Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-06-21
2004-07-20
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S515000, C525S240000
Reexamination Certificate
active
06765048
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to polyethylene compositions that are new and useful, and films produced therefrom that are characterized by preferably having increased moisture vapor transmission rates (MVTR).
BACKGROUND OF THE INVENTION
It is known that properly formulated films fabricated from polyethylene that have been filled with solid particles (e.g., a mineral such as calcium carbonate) can be stretched under appropriate conditions creating a porous structure that allows for the diffusion of water vapor while providing a liquid water barrier. This is a desirable property in markets such as hygienics, industrial and medical. Indeed, a major consideration in the comfort of a garment is its ability to maintain a balance between heat production and heat loss. The loss of heat through clothing may occur through direct dry heat loss or by moisture evaporation. In respect to the latter, the moisture vapor transmission rate of the material utilized in forming the garment is generally related to the breathability of the material. Breathability is the ability to diffuse moisture/water vapor through a film or garment. In addition to this property, there are many applications requiring that the material used in preparing the garment be impermeable to a liquid. Such applications include diaper back sheets, sanitary napkins, medical protective garments, surgical incise drapes, transdermal patches, wound care bandages and dressings, intravenous site dressings, ostomy site dressings, breathable housewrap, among others.
Films which are permeable to water vapor and are porous but yet are intended to be impermeable to a liquid are described in U.S. Pat. Nos. 4,626,252 and 5,073,316. As disclosed, a porous film is obtained by mixing a polyolefin resin, an inorganic filler and a plasticizer; forming a film from the mixture; and uniaxially or biaxially stretching the film. Films of this type are also disclosed in U.S. Pat. No. 5,998,505 and PCT International Application Publication No. WO 98/05501.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide new and improved polyethylene compositions or blends.
It is a further object of this invention to provide novel polyethylene compositions or blends of specific polyethylenes and fillers.
It is a further object of this invention to provide novel films produced from the novel compositions, which films are characterized by having improved moisture vapor transmission rates (MVTR).
These and other objects and advantages of the present invention will be apparent to those skilled in the art from the following detailed description and claims.
In accordance with the present invention, it has been found that the above and still further objects are achieved by combining a first polyethylene component having specified characteristics and a second polyethylene component having specified characteristics to provide a novel resultant polyethylene composition. A filler is added to the novel polyethylene composition to provide novel polyethylene-filler compositions that are suitable to provide novel films that are characterized by having increased moisture vapor transmission rates (MVTR). The compositions and films are useful in many applications.
More particularly, in accordance with the present invention, a polyethylene composition is provided comprising (a) a first ethylene homopolymer or ethylene interpolymer having a density of from about 0.88 to about 0.93 g/cc (grams/cubic centimeter), a melt index of from about 1 to about 5 g/10 min (grams/10 minutes), a weight percent high temperature fraction (% HT) as determined by TREF of about 0 to about 50 weight %, and a number average molecular weight (Mn) of the HT fraction collected during the TREF procedure of about 15,000 to about 100,000 g/mol, present in an amount of from about 1 to about 99 weight percent (%) based on the total weight of the polyethylene composition; and
(b) a second ethylene homopolymer or ethylene interpolymer having a density of from about 0.93 to about 0.97 g/cc, a melt index of from about 1 to about 50 g/10 min, a % HT fraction as determined by TREF of about 25 to about 100 weight %, and a Mn of the HT fraction collected during the TREF procedure of about 15,000 to about 100,000 g/mol, present in an amount of from about 1 to about 99 weight %, based on the total weight of the polyethylene composition.
The resultant polyethylene composition is characterized by having a density of from about 0.91 to about 0.93 g/cc, a melt index of from about 1 to about 5 g/10 min, a weight percent high temperature fraction (% HT) as determined by TREF of about 25 to about 50 weight %, and a number average molecular weight (Mn) of the HT fraction collected during the TREF procedure of from about 35,000 to about 52,000 g/mol. In a preferred embodiment, the % HT of the polyethylene composition ranges from about 30 to about 45 weight %.
Further, in accordance with the present invention, there is provided a novel polyethylene-filler composition comprising
(i) a polyethylene composition, as hereinbefore defined, having a density of from about 0.91 to about 0.93 g/cc, a melt index of from about 1 to about 5 g/10 min, a weight percent high temperature fraction (% HT) as determined by TREF of about 25 to about 50 weight %, and a number average molecular weight (Mn) of the HT fraction collected during the TREF procedure of from about 35,000 to about 52,000 g/mol with the % HT of the polyethylene composition preferably ranging from about 30 to about 45 weight %; the polyethylene composition comprises
(a) a first ethylene homopolymer or ethylene interpolymer having a density of from about 0.88 to about 0.93 g/cc (grams/cubic centimeter), and a melt index of from about 1 to about 5 g/10 min (grams/10 minutes), a % HT as determined by TREF of about 0 to about 50 weight %, and a Mn of the HT fraction collected during the TREF procedure of about 15,000 to about 100,000 g/mol, present in an amount of from about 1 to about 99 weight percent (%) based on the total polyethylene composition; and
(b) a second ethylene homopolymer or ethylene interpolymer having a density of from about 0.93 to about 0.97 g/cc, a melt index of from about 1 to about 50 g/10 min, a % HT fraction as determined by TREF of about 25 to about 100 weight %, and a Mn of the HT fraction collected during the TREF procedure of about 15,000 to about 100,000 g/mol, present in an amount of from about 1 to about 99 weight %, based on the total weight of the polyethylene composition, the polyethylene composition preferably being present in the polyethylene-filler composition in an amount of from about 20 to about 80 weight percent (%) based on the total weight of the polyethylene-filler composition; and
(ii) a filler present in an effective amount, such that a film formed from the novel polyethylene-filler composition has increased MVTR; preferably the filler is present in the polyethylene-filler composition in an amount of from about 20 to about 80 weight percent, based on the total weight of the polyethylene-filler composition.
In addition to the novel compositions, the present invention is also directed to films formed from the novel polyethylene-filler compositions that are characterized by having increased moisture vapor transmission rates.
Additionally, the present invention is directed to articles of manufacture incorporating the novel compositions and novel films of the present invention. Such articles include garments, diapers, sanitary napkins, medical protective garments, surgical incise drapes, transdermal patches, wound care bandages and dressings, intravenous site dressings, and ostomy site dressings, and others, incorporating the novel compositions and films of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The polyethylene compositions of the present invention comprise
(a) a first ethylene homopolymer or ethylene interpolymer having a density of from about 0.88 to about 0.93 g/cc (grams/cubic centimeter), a melt index of from about 1 to about 5 g/10 min (grams/10 minutes), a % HT
Barr Dennis Brannon
Crawford Emmett Dudley
Dohrer Kathryn Kobes
Edmund Mark Alan
Hale Wesley Raymond
Eastman Chemical Company
Graves, Jr. Bernard J.
Wood Jonathan D.
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