Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1995-05-17
2001-05-01
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C442S181000, C442S199000, C442S164000, C428S365000, C428S219000, C428S220000, C428S374000
Reexamination Certificate
active
06224977
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to fibers and the nonwoven fabric or web which is formed from such fibers of a thermoplastic resin, and laminates using such a web as a component.
Thermoplastic resins have been extruded to form fibers, fabrics and webs for a number of years. The most common thermoplastics for this application are polyolefins, particularly polypropylene. Other materials such as polyesters, polyetheresters, polyamides and polyurethanes are also used to form nonwoven fabrics.
Nonwoven fabrics or webs are useful for a wide variety of applications such as diapers, feminine hygiene products, towels, and recreational or protective fabrics. The nonwoven fabrics used in these applications are often in the form of laminates like spunbond/meltblown/spunbond (SMS) laminates. The strength of a nonwoven fabric is one of the most desired characteristics. Higher strength webs allow thinner layers of material to be used to give strength equivalent to a thicker layer, thereby giving the consumer of any product of which the web is a part, a cost, bulk and weight savings. It is also very desirable that such webs, especially when used in consumer products such as diapers or feminine hygiene products, be very soft.
It is an object of this invention to provide a polypropylene nonwoven fabric or web which is very strong and yet is also very soft.
SUMMARY OF THE INVENTION
A very strong yet soft nonwoven polypropylene fiber is provided. A fabric is also provided which is a web of the fibers which are produced from a blend of polyolefin polymers. One polymer is a highly crystalline polypropylene. The second polymer is a copolymer of polypropylene and polyethylene in which the ethylene has a random and block distribution, hence a “random block copolymer”.
A fabric made from fibers of the above blend is surprisingly strong, believed by the inventors to be due to incomplete melting at the bond points during bonding because of the high crystallinity of the polypropylene.
The nonwoven fabric of this invention may be used in products such as, for example, garments, personal care products, medical products, protective covers and outdoor fabrics.
Definitions
As used herein the term “nonwoven fabric or web” means a web having a structure of individual fibers or threads which are interlaid, but not in a regular, repetitive manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).
As used herein the term “microfibers” means small diameter fibers having an average diameter not greater than about 50 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibers may have an average diameter of from about 2 microns to about 40 microns. The diameter of, for example, a polypropylene fiber given in microns, may be converted to denier by squaring, and multiplying the result by 0.00629, thus, a 15 micron polypropylene fiber has a denier of about 1.42 (15
2
×0.00629=1.415).
As used herein the term “spunbonded fibers” refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries of a spinnerette with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. Nos. 3,502,763 and 3,909,009 to Levy, and U.S. Pat. No. 3,542,615 to Dobo et al. Spunbond fibers are generally continuous and larger than 7 microns in diameter, more particularly, they are usually between about 10 and 20 microns.
As used herein the term “meltblown fibers” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin. Meltblown fibers are microfibers which are generally smaller than 10 microns in diameter.
As used herein the term “bicomponent” refers to fibers which have been formed from at least two polymers extruded from separate extruders but spun together to form one fiber. The configuration of such a bicomponent fiber may be, for example, a sheath/core arrangement wherein one polymer is surrounded by another or may be a side by side arrangement as illustrated in U.S. Pat. No. 5,108,820 to Kaneko et al., or an “islands-in-the-sea” arrangement. The polymers may be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios.
As used herein the term “biconstituent fibers” refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend. Biconstituent fibers are sometimes referred to as multiconstituent fibers and usually have fibrils of one of the polymers within a matrix of the major polymer. Fibers of this general type are discussed in, for example, U.S. Pat. No. 5,108,827 to Gessner.
As used herein the term “blend” means a mixture of two or more polymers while the term “alloy” means a sub-class of blends wherein the components are immiscible but have been compatibilized. “Miscibility” and “immiscibility” are defined as blends having negative and positive values, respectively, for the free energy of mixing. Further, “compatibilization” is defined as the process of modifying the interfacial properties of an immiscible polymer blend in order to make an alloy. Note that a fiber formed from a blend of polymers need not have the fibrils characteristic of biconstituent fibers.
As used herein, the term “machine direction” or MD means the length of a fabric as it is produced. The term “cross machine direction” or CD means the width of fabric, i.e. a direction generally perpendicular to the MD.
As used herein, the term “garment” means any type of apparel which may be worn. This includes industrial work wear and coveralls, undergarments, pants, shirts, jackets, gloves, socks, and the like.
As used herein, the term “medical product” means surgical gowns and drapes, face masks, head coverings, shoe coverings wound dressings, bandages, sterilization wraps, and the like for medical, dental or veterinary applications.
As used herein, the term “personal care product” means wipers, diapers, training pants, absorbent underpants, adult incontinence products, and feminine hygiene products.
As used herein, the term “protective cover” means a cover for vehicles such as cars, trucks, boats, airplanes, motorcycles, bicycles, golf carts, etc., covers for equipment often left outdoors like grills, yard and garden equipment (mowers, roto-tillers, etc.) and lawn furniture, as well as floor coverings, table cloths and picnic area covers.
As used herein, the term “outdoor fabric” means a fabric which is primarily, though not exclusively, used outdoors. Outdoor fabric includes fabric used in protective covers, camper/trailer fabric, tarpaulins, awnings, canopies, tents, agricultural fabrics and outdoor apparel such as head coverings, industrial work wear and coveralls, pants, shirts, jackets, gloves, socks, shoe coverings, and the like.
Test Methods
Cup Crush: The softness of a nonwoven fabric may be measured according to the “cup crush” test. A lower cup crush value indicates a softer
Kobylivker Peter Michailovich
Lance Roger Lynwood
Ofosu Simon Kwame
Shawver Susan Elaine
Dean, Jr. Ralph H.
Dixon Merrick
Kimberly--Clark Worldwide, Inc.
Robinson James B.
LandOfFree
Soft and strong thermoplastic polymer nonwoven fabric does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Soft and strong thermoplastic polymer nonwoven fabric, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Soft and strong thermoplastic polymer nonwoven fabric will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2553554