US20070248823A1

US20070248823A1 - Fluorine containing copolymer fiber and fabric

Info

Publication number: US20070248823A1
Application number: US11/790,058
Authority: US
Inventors: Chris S. Moore; Katsuyoshi Kubo
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2006-04-24
Filing date: 2007-04-23
Publication date: 2007-10-25

Abstract

A fiber contains a fluorine-containing copolymer such as EFEP. The fiber is preferably a non-hollow monofilament fiber, and the fluorine-containing copolymer preferably has a melt index (MI) below 100. A fabric contains a fluorine-containing copolymer such as EFEP. The fabric preferably includes non-hollow monofilament fibers, which contain the fluorine-containing copolymer, and the fluorine-containing copolymer preferably has a melt index (MI) below 100.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Application No. 60/794,101 filed on Apr. 24, 2006. The entire disclosure of U.S. Provisional Application No. 60/794,101 is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to copolymer fibers and fabrics. More specifically, the present invention relates to fibers and fabrics, which contain a fluorine containing copolymer such as ethylene-perfluoroethylenepropene (EFEP).
2. Background Information
Generally, fluorine-containing polymers are known to have good heat resistance, chemical resistance, weather resistance, low friction, and demonstrate good electrical insulation properties. Accordingly, fluorine-containing polymers are widely used for a variety of industrial purposes. However, fluorine-containing polymers are generally weaker than other industrial resins, and tend to have low friction, chemically inert surfaces that do not adhere to other materials well. Therefore, it is difficult to bond fluorine-containing polymers to another material or polymer directly. Additionally, fluorine containing polymers typically have relatively high melting points, relatively high molecular weights and relatively low melt flow indices, which can complicate the use of such materials.
Fibers that contain melt processable fluorine-containing polymers and fabrics constructed using such fibers are in limited use. Specifically, fluorine-containing polymers are generally weak, and thus, are typically combined with stronger, non-fluorine containing polymers if utilized in fibers and/or fabrics. For example, International Application Publication No. WO03/004738 and Japanese Patent Application Publication No. 2000-144533 disclose sheath-core type bicomponent fibers that utilize PVDF, ECTFE, and ETFE as a sheath material. U.S. Patent Application Publication No. 2003/0175514 and U.S. Pat. No. 6,287,689 disclose sheath-core type bicomponent filament fibers that utilize halogenated polymers.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved fiber and an improved fabric. This invention addresses these needs in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

Ethylene-perfluoroethylenepropene copolymer (hereinafter “EFEP”) has been developed by Daikin Industries, Ltd. (Osaka, Japan). EFEP has excellent chemical resistance, a relatively low melting point and a relatively low melt index. Moreover, EFEP possesses a superior ability to bond to glass, metal and polyamide surfaces, as well as other desirable physical properties.
U.S. Pat. No. 6,680,124 discloses fluorine-containing ethylenic polymer adhesives having carbonate groups and/or carboxyl halide groups, which can adhere to a substrate made of metal, glass, or resin.
Fluorine-containing ethylenic polymers such as EFEP are relatively new, and all of the benefits associated with such polymers have not been fully realized. In other words, these polymers have not yet been used in many applications due to unique characteristics of these polymers as compared with more conventional polymers.
One objective of the present invention to provide fibers and fabrics that contain a fluorine containing copolymer such as EFEP, which are relatively strong and have excellent chemical resistance.
Another object of the present invention is to provide fibers and fabrics that utilize a fluorine containing copolymer such as EFEP, which are relatively simple and relatively inexpensive to manufacture as compared to their benefits.
The foregoing objects can basically be attained by providing a non-hollow, monofilament fiber consisting essentially of a fluorine containing copolymer having a melt index (MI) of less than 100.
The foregoing objects can also basically be attached by providing a fabric, which comprises non-hollow, monofilament fibers consisting essentially of a fluorine containing copolymer having a melt index (MI) less than 100.
The forgoing objects can also basically be attained by providing a fiber containing EFEP.
The forgoing objects can also basically be attained by providing a fabric containing EFEP.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a schematic view of monofilament fiber consisting essentially of EFEP in accordance with an embodiment of the present invention;

FIG. 2 is a schematic view of a woven fabric made from a fiber in accordance with an embodiment of the present invention;

FIG. 3 is a schematic view of a non-woven melt-blown fabric made by randomly arranging a single type of fiber in accordance with an embodiment of the present invention;

FIG. 4 is an example of an extrusion apparatus used to manufacture a filament fiber in accordance with the present invention;

FIG. 5 is another example of an extrusion apparatus used to manufacture a filament fiber in accordance with the present invention;

FIG. 6 is an example of a melt blowing apparatus used to manufacture a non-woven, melt-blown fabric using fibers in accordance with the present invention;

FIG. 7 is a schematic view of a non-woven fabric having EFEP staple fibers mechanically blended with non-EFEP staple fibers in accordance with an embodiment of the present invention;

FIG. 8 is a schematic view of a non-woven fabric having EFEP fibers melt blown onto non-EFEP staple fibers in accordance with an embodiment of the present invention; and

FIG. 9 is a schematic view of a non-woven fabric having EFEP fibers melt blown onto non-EFEP filament fibers in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
Referring initially to FIG. 1, a non-hollow fiber 100 is schematically illustrated in accordance with the present invention. The non-hollow fiber 100 is preferably a monofilament fiber which can be utilized in filament form to make various fabrics, or which can be cut into staple fibers to make various fabrics, as explained below. The term “monofilament fiber” as used herein refers to a fiber constructed essentially of a single material. The fiber(s) and fabric(s) in accordance with the present invention will now be explained.
A non-hollow fiber in accordance with the present invention contains a fluorine containing polymer. More specifically, a non-hollow fiber in accordance with the present invention preferably contains an ethylenic polymer (Ethylene (Et) Tetrafluoroethylene (TFE) Hexafluoropropylene (HFP), hereinafter referred to as EFEP) that is generally expressed as the following formula:
where l, m, and n are natural numbers and X and Y are functional groups. As mentioned above, a non-hollow fiber 100 in accordance with the present invention is preferably a monofilament fiber. Thus, the fiber 100 is preferably constructed essentially of EFEP. In any case, a non-hollow fiber in accordance with the present invention preferably contains EFEP at least at its entire outer surface such that at least 25% (by weight) of the fiber is preferably constructed of EFEP. Preferably, a non hollow fiber in accordance with the present invention is solely made of EFEP. In other words, as close to 100% of the non-hollow fiber is constructed of EFEP (i.e., except for trace elements and/or impurities) as possible.
The functional groups expressed as X and Y above are preferably carboxyl groups. Such carboxyl groups should preferably include a carbonate group and/or a carboxyl halide group.
The carbonate group in the fluorine containing polymer is generally expressed as
—OC(═O)O—R
where R is a hydrogen atom; or an organic group such as an alkyl group with 1-20 carbon atoms; or an alkyl group with 2-20 carbon atoms and an ether coupling; or an element of the first, second, or the seventh group. Examples of such carbonate group include:
—OC(═O)OCH₃;
—OC(═O)OC₃H₇;
—OC(═O)OC₈H₁₇; and
—OC(═O)OCH₂CH₂OCH₂CH₃.
The carboxyl halide group is generally expressed as:
—COY
where Y is halogen. Examples of such carboxyl halide group include:
—COCl; and
—COF.
Such EFEP (represented by the above formulae) generally results from copolymerization of, for example, at least: 20 to 90 mole percent of tetrafluoroethylene; 10 to 80 mole percent of ethylene; and 1 to 70 mole percent of a compound represented by the general formula:
CF₂═CF—Rf¹
where Rf¹represents CF₃or ORf², Rf²represents a perfluoroalkyl group having 1 to 5 carbon atoms.
EFEP copolymer should contain preferably 5-20 mol %, more preferably 8-17 mol %, of HFP units. Such EFEP copolymer can contain, in addition to the monomer units that are contributed by TFE, HFP and Et, one type or more than one types of additional monomers, as long as preferable properties of the resulting EFEP copolymer are unaffected. Examples of such additional monomers include trichlorofluoroethylene, propylene, and monomers expressed as the following formulae:
CX³ ₂═CX⁴—(CF₂)n-X⁵
CF₂═CF—O—Rf³
where X³is either a hydrogen atom or a fluorine atom, X⁴is either a hydrogen atom or a fluorine atom, with X³and X⁴being either the same or different, X⁵is a hydrogen atom, a fluorine atom, or a chlorine atom, and n is a natural number of 1-10, and where Rf³is a perfluoroalkyl group with carbon number 1-5. It is generally well known how to construct EFEP having the composition described above. Such EFEP is usually produced in pellet form by Daikin Industries, Ltd. (Osaka, Japan).
EFEP constructed as described above has a relatively low melting point, which is approximately between 165° C. and 195° C., i.e., less than 200° C. In any case, EFEP constructed as described above has a melting point below 240° C., preferably well below 240° C. Also, EFEP constructed as described above has is generally known to have desirably adhesive properties (e.g., superior adhesiveness). Finally, EFEP constructed as described above has a relatively low melt index (MI) of about 35. In any case, EFEP constructed as described above has a melt index (MI) below 100.
“Fibers” as used herein include filament fibers as well as staple fibers and yarns made of staple fibers. A “filament fiber” as used herein means a fiber having a continuously elongated shape with an indefinite length. Filament fibers generally have a fineness of approximately 44-700 denier, although the fineness of filaments as used herein is not limited to this range. A “monofilament fiber” as used herein means a filament fiber constructed essentially of a single type of thermoplastic material, as mentioned above. A “staple fiber” as used herein means relatively short pieces of filament fibers that are formed by mechanically cutting or shredding filament fibers or by skiving films. “Fabrics” as used herein include materials that are formed with fibers using woven or knit methods such as weaving, knitting, and plaiting, or with non-woven methods such as carding, felting, air-laying, wet-laying, melt-blowing, needle-punching, hydro-entangling, adhesive bonding, electro-spinning, and solvent-spinning, or using other techniques such as braiding.
Fabrics are made of filament fibers and/or staple fibers. Some of the most common methods of manufacturing fabrics from filament fibers and staple fibers include woven or knit methods such as weaving, knitting, and plaiting, as well as non-woven web forming methods such as carding, needle-punching, air-laying, wet-laying, melt-blowing, hydro-entangling, electro-spinning, solvent spinning and other techniques like braiding. In the non-woven mechanical fabric forming methods, the filaments may be converted into staple fibers and blended with other materials or fibers.
Fabrics can be made from a single type of fiber, or from more than one type of fiber. FIGS. 2 and 3 show examples of fabrics that are made from a single type of fiber, with FIG. 2 being a woven fabric and FIG. 3 being a non-woven fabric. In other words, the woven fabric of FIG. 2 could include different types of fibers such as some EFEP fibers and some non-EFEP fibers woven into the construction since most knitting or weaving machines can feed different types of fibers to make one knit or woven fabric. FIGS. 7-9 show examples of fabrics that are made from two different types of fibers, one being EFEP fibers and the other being non-EFEP fibers. Such EFEP fibers and non-EFEP fibers may be in the form of either fibers or fabrics prior to being combined into one composite fabric. These composites of EFEP and non-EFEP fibers can be used to reduce overall costs of composite fabrics by using lower cost non-EFEP fibers in ways that don't compromise the benefits of using EFEP in a product. A demonstration of such an application is where an EFEP fabric is used as a filter to separate water from compressed air systems, where the fine filtration and pressure support is provided by a lower cost conventional fiber underneath the more expensive EFEP water separating surface fabric.
The non-woven forming methods can be performed by, for example, a melt-blown process, with molten filaments being laid out to form a fabric made of a single type of fiber, or onto other types of fibers or fabrics such as nylon and/or polyester to form a composite fabric. For example, FIG. 7 is a magnified schematic view of a non-woven fabric in which EFEP staple fibers (shown in black) are mechanically blended with non-EFEP staple fibers (shown in grey). FIG. 8 is a magnified schematic view of a non-woven fabric in which EFEP filament fibers (shown in black) are melt blown onto non-EFEP staple fibers (shown in grey). FIG. 9 is a magnified schematic view of a non-woven fabric in which EFEP filament fibers (shown in black) are melt blown onto non-EFEP filament fibers (shown in grey).
Fluorine containing polymer filament fibers including those specifically containing EFEP can be generally manufactured by melting pellets of the fluorine containing polymer (EFEP) and extruding or melt spinning the melted polymer. Monofilament fibers are manufactured using a melt spinning apparatus such as the ones shown in FIGS. 4 and 5. Although the size and the scope of the extrusion process will vary depending upon commercial or laboratory requirements, the basic principles of melt spinning remain the same for most thermoplastic polymers. In the case of fine or low denier filament fibers, these fibers can be cooled using an air quenching system which speeds the cooling of the molten fiber as it exits the spinbeam, thus allowing the fine fibers to develop physical properties. Heavy or high-denier filament fibers, on the other hand, require more cooling time or heat transfer after the molten fiber exits the spinbeam to cool or “quench” and develop physical properties. A melt spinning system having a longer quenching distance (such as the one shown in FIG. 5), the use of cold quench air, and the use of water can assist in the production of such heavier filament fibers. More specifically, FIG. 4 shows a horizontal spinning arrangement more commonly used to produce heavy denier fibers. The melt spinning apparatus can further include a water bath in order to quench or cool the fibers so that the fibers can be drawn to increase strength and reduce denier, as well as to increase production speeds. FIG. 5 shows a vertical arrangement, which is commonly used to produce finer denier fibers. The extrusion equipment (from the pellet feed hopper 1′ to the Spinpack Zone C) of FIG. 5 is similar to that of FIG. 4.
In melt spinning apparatuses shown in FIGS. 4 and 5, the solid EFEP pellets are converted into a molten, pressurized viscous liquid by the extruder designated in heat zone #A+B. The pressurized liquid of EFEP is then metered and further pressurized at the Spinpack with gearpump zone #C, and fed into a die or orifice, thereby being formed into molten fibers. In the melt spinning apparatus shown in FIGS. 4 and 5, pellets of EFEP are supplied to a pellet feed hopper 1. The EFEP pellets are transported by a rotating extruder screw inside of a heated metal barrel. The internally rotating screw is powered by an electric motor and gear reducer and is machined into three connected sections, which are commonly called “feed”, “compression”, and “metering”.
The melt extrusion process begins as the solid pellets are supplied to the open flights of a rotating extrusion screw inside of a heated metal barrel beneath the pellet feed hopper 1 (feed zone). While the pellets are in the feed zone, the polymer pellets are transported forward and heated without being completely melted. Since the pellets are not totally melted into liquid, the pellets can be transported and move from the deeper flights of the feed zone to the shallower flights of the compression zone by the rotation of the screw. In this manner, these pellets are forced down the hot barrel through the “feed” section into the tighter spaces of the “compression” section of the screw. In the “compression” zone, as the flights of the screw becomes shallower, the core or “root” of the screw becomes thicker thus compressing the pellets together and forcing them into more complete contact with the heated barrel. This close contact to the heat from the metal barrel in the compression zone helps the pellets to melt rapidly. The melting pellets are further transported down the screw, exiting the “compression” section into the final “metering” section, where they complete the melting process and are forced under pressure into the “spinpack”. Once the molten polymer enters the “spinpack,” the pressure is further increased by the “gearpump” in zone #C, which continuously provides a precise amount of molten polymer to the “spinneret”. This spinneret in zone #C acts as an extrusion die with precision holes or shapes of holes drilled or cut through its thickness, through which the polymer is forced under pressure to exit the “spinpack” to form molten filament fibers.
The molten EFEP filament fiber is cooled while being drawn from the spinneret and passed over godets 4 (roll #1 and roll #2). The filament fiber cools and gains strength as it is passed over the godets 4. The speeds at which these godet rolls #1 and #2 operate are independently controlled to allow the filament fiber to accelerate and be stabilized as the filament fiber is wound up onto tubes or bobbins on the winder 5. Furthermore, a spin finish is often applied to the filament fibers to ease downstream processing and handling and/or to ease the removal from the tubes.
When woven or knit fabrics are to be manufactured from the filament fibers, the filament fiber is unwound from these bobbins or tubes to be knit or woven to make a fabric. Non-woven fabrics can also be manufactured from the filament fibers by mechanical forming methods, or combined into composite fabrics using a melt blowing processes. FIG. 2 shows an example of such woven fabric 300, which is formed of a monofilament fiber 100. FIG. 3 shows an example of a non-woven fabric which can be manufactured by melt-blowing a single type of filament fiber.
To manufacture staple fibers out of the filament fiber, the filament fiber is typically fed into a cutting device called a “tow cutter” directly off of the godets 4, instead of being fed into the winder 5, so that the filament fiber is cut into staple pieces and deposited into a storage container. Staple fibers can also be made by cutting filament fibers into small pieces off the bobbins or tubes which have been made using equipment similar to those shown in FIGS. 4 and 5. Staple fibers can be formed into a yarn by mechanically spinning such staple fibers. Also, it will be apparent to those skilled in the art from this disclosure that non-woven fabrics can be manufactured from such staple fibers by any non-woven processing method well known to those skilled in the art, such as carding, web forming, felting, air-laying, wet-laying, melt blowing, needle-punching, electro-spinning, solvent-spinning, and hydro-entangling processes. Braiding can also be used to form yarns, ropes, cables and other composite forms.
An extrusion apparatus for manufacturing EFEP monofilament fibers can be alternatively structured as shown in FIG. 5. In the extrusion apparatus of FIG. 5, the pellet feed hopper 1′, the extruder heat zones 2′, and the gear pump and spinpack 3′ are placed on an elevated platform 6′ for better air quenching of the extruded filament. The platform 6′ is preferably placed at the height of at least 9 to 10 feet to ensure cooling of the filament fiber. The additional drop permits a higher draw ratio for the fiber, which increases the speed of production and the tenacity of the cooled fiber. The cooler-drawn fiber is wound onto the tubes of the winder 5′ more uniformly and unwinds with an improved take off performance. Furthermore, the increased height allows for the production of finer or lower-denier fibers. Such finer or lower-denier fibers make fabrics that are lower in weight and higher in capture rates of small particles, and therefore are particularly useful in filtration applications. Finer or lower-denier fibers also bend more easily which improves mechanical blending, needlepunching into nonwovens and mechanical spinning into staple fibers since the fibers can wrap around each other more effectively.
FIG. 6 shows a typical melt blowing apparatus used to make non-woven fabrics. Pellets are loaded into the extruder hopper, and then melted in a way similar to the extrusion process previously described, and detailed in FIGS. 4 and 5. The molten polymer is fed into a melt blowing die at the end of the extruder by the extruder screw and/or a gear pump. The molten polymer is forced out of the melt blowing die through a series of holes similar to the holes formed in the spinneret shown in FIGS. 4 and 5, except that the melt blowing apparatus of FIG. 6 usually has many more holes arranged in a linear array.
As the molten polymer is spun out of the melt die holes, hot air is blown from a hot air supply tube past the die and the molten fiber, which helps to attenuate the molten fiber and reduce its diameter. The hot air also transports the molten fiber from the melt blowing die and deposits it in a random pattern onto a hot melt blowing collection zone of the conveyor belt, creating a non-woven fabric. This hot air accelerates the filaments from the outlet of the extrusion die and reduces substantially the fiber diameter as the cooling fibers are blown out onto the conveyor belt or collection device. The cooling fibers are laid out onto the porous conveyor belt such that the tacky fibers bond to one another and form a strong randomly oriented fabric. The speed at which the conveyor belt operates, die to the collector belt distance (DCD), temperature of the fibers, and the rate with which the molten fiber is forced from the die control the thickness and weight of the non-woven fabric produced with this apparatus. The newly laid non-woven fabric cools as the conveyor moves the fabric away from the hot melt blowing collection zone and allows the fabric to cool and be wound up on a roll or tube for later use or conversion. Extrusion temperatures, hot air temperatures, hole diameter, air gap size, conveyor speed, and melt rheology of the polymer are just some of the variables that can be varied to adjust the quality of the melt blown fabrics.

EXAMPLE 1

Examples of monofilament fibers that were manufactured using the extrusion apparatus shown in FIG. 4 will be provided herein.
During the manufacturing of EFEP monofilament fibers, conditions were varied to produce fibers of varying diameters or denier (grams per 9000 meter of length), tenacity in grams per denier, and elongation to break. These monofilament spinning conditions are shown in table 1-1.

TABLE 1-1

						Roll	Roll
	Zone A	Zone B	Zone C	Pressure	Gearpump	#	1	#2	Winder	Traverse	Average	Elongation	Tenacity
Sample #	° C.	° C.	° C.	bar	% output	mpm	mpm	mpm	0–60 Hz	Denier	at break %	gpd

1	203	235	243–244	34.5	25	180	200	304	33 Hz	342	81%	0.56
2	203	235	244	34.5	25	170	200	304	33 Hz	294	95%	0.74
3	203	235	250	34.5	20	160	200	304	25 Hz	147	204%	0.8
4	203	235	246	34.5	20	160	200	304	25 Hz	147	171%	0.83
5	203	235	247	34.5	20	160	200	304	25 Hz	150	169%	0.75
6	203	235	247	34.5	15	160	200	243	25 Hz	93	152%	0.8
7	203	235	247–248	34.5	17	125	150	243	25 Hz	106	156%	0.79
8	203	235	247	34.5	17	400	500	608	25 Hz	44	64%	1.17
9	203	235	247	34.5	25	400	500	608	25 Hz	102	99%	0.86

The conditions under which the EFEP fibers shown in table 1-1 were produced are as follows. The extruder barrel temperature setting was 203° C. for zone #A, and 235° C. for zone #B. The temperature at zone #C, which includes the gear pump and the spinneret 3, was varied from 243 to 250° C. The speed of the gear pump 3 was varied in the range of 15 to 25% of the total drive speed. The surface speed of the first position godet roll # 1 was varied from 125 to 400 meters per minute (mpm), while the rate of the second godet roll # 2 was varied from 150 to 500 mpm. The surface speed of the rotating godet roll # 1 was always lower than the surface speed of the rotating godet roll # 2 in order to provide tension on the monofilament fiber. In addition, the speed of the surface driven winder 5 was varied from 243 to 608 mpm, while the winder traverse frequency was varied from 25 to 33 hertz. Overall, when the rates of the godets 4 and winder 5 were changed, they were always changed to increase, rather than decrease, the filament speed toward the winder, in order to maintain the fiber tension to the winder 5.
As seen in Table 1-1, samples Nos. 3-7 demonstrated high elongation to break, while sample No. 8 demonstrated high tenacity.
Additional spinning of EFEP fibers using equipment similar to that shown in FIG. 5 were conducted with two different grades of resin which demonstrate the advantages of producing monofilament fiber with increased air quench. Table 1-1A shows fiber made using higher orientation and longer air quench to produce fibers from RP-5000 grade EFEP with average tenacity of 1.74 grams per denier breaking strength and elongation to failure of ˜24%. Grade RP-4020 was spun into monofilament using the same equipment represented by FIG. 5 resulting in a 107.1 denier fiber with ˜93% elongation to failure and with a tenacity of over 2 grams per denier.

TABLE 1-1A

	EFEP		Elongation to	Tenacity
Sample	Grade	Denier	break %	gpd

DCEFUG-2	RP-5000	55.4	23.98	1.74
DCEFUG-3	RP-4020	107.1	93.45	2.01

EXAMPLE 2

Experiments were performed with EFEP RP-5000, available from Daikin America, Inc. (Orangeburg, N.Y.), using polymers with relatively high molecular weight and low melt flow indexes of around 35, on melt blowing equipment similar to that shown in FIG. 6. The conditions and results of the experiment are summarized in Table 1-2. However, by increasing the melt blowing die hole diameter to 0.025 inches (0.635 mm), and by increasing the hot air temperature and the air gap to 0.1 inch (2.54 mm), fabrics with fiber diameters down to 8 microns, with average diameters of 13.75 microns, were produced. Particularly, melt blown fabrics that weigh 180 grams per square meter (sample #3) down to 25 grams per square meter (sample #4) were produced using standard 35 melt flow index RP-5000 polymer.

DAIKIN EFEP RP-5000 Resin

Nonwoven Melt Blowing Test # 1

TABLE 1-2

			Hole
	Melt		size	Holes per	Air gap
Sample #	Die	Air Temp	(mm)	six inch die	(mm)	Web comments	Fiber diameter

1	260° C.	277° C.	0.635	120	2.032	weak web formed	~25 micron
2	288° C.	299° C.	0.635	120	2.032	delicate web formed	~20 micron
3	260° C.	329° C.	0.635	120	2.032	180 grams/m2 web	below 20 micron
4	260° C.	329° C.	0.635	120	.2.54	25 grams/m2 web	~8 micron,
							13.75 micron
							average

EFEP polymer pellets were loaded into the feed hopper of the melt blowing machine extruder and melted in a process similar to the melt spinning machine of example #1. Molten EFEP polymer passes from the extruder, thru a ˜200 micron stainless steel screen filter, into the coat hanger style melt blowing die. The pressurized molten EFEP viscous resin is forced into the 10/1 length to diameter (L/D) ratio lead holes, exiting the melt blowing die thru the 120 linearly arranged 0.025 inch (0.635 mm) holes. The hot air (ranging from 277° C. to 329° C.) slows the cooling of the viscous liquid polymer and transports the stretching fibers onto the conveyor belt. This hot air blows the fibers onto the belt while creating a heated environment around the stretching fibers allowing them to reduce in diameter in a controlled way as they leave the melt blowing die holes. Higher air temperatures at the die with increased air velocity created finer diameter fibers. Increasing the air gap around the melt blowing die where the hot air carries the fibers away from the melt blowing die holes also resulted in finer fiber diameter.

EXAMPLE #3

RP-5000 EFEP polymer pellets with a melt index of 78.7 were produced by Daikin for melt blowing trials on the same equipment as used in Example #2. The six inch (152.4 mm wide die) melt blowing machine with a 1.25 inch (˜32 mm) diameter single screw extruder with 30/1 L/D was set up using a 120 hole melt blowing die with 25 mil (0.635 mm) orifices and 0.1 inch (2.54 mm) air gap with a 10 inch (25.4 cm) die to collector distance (DCD), in this case the collector was a continuous loop take up belt. Higher production rates were obtained with the 78.7 MI EFEP resin with extruder rpm of over 8.4 and conveyor belt speeds of over 3.5 meters per minute.

TABLE 1-3

					MB	Air			average
	Zone
1	Zone 2	Zone 3	Zone 4	Die	temp	Air		fiber	minimum	maximum
Sample	(° C.)	(° C.)	(° C.)	(° C.)	(° C.)	(° C.)	pressure	gsm	dia.(microns)	(microns)	(microns)

MB2-1	240	270	275	256	255	321	0.69 bar	46	11.06	7.92	13.39
MB2-3	249	260	260	257	256	327	0.69 bar	96	8.32	5.05	10.01
MB2-6	253	261	268	252	282	332	1.03 bar	100	6.39	4.51	8.89

With improved operating conditions nonwoven webs with fiber diameters as low as 4.5 microns were able to be produced with average diameters as low as 6.39 micron for sample MB2-6 as evidenced by fiber diameter analysis using an electron microscope in Table 1-4. The webs produced in Example #3 had very good fiber diameter uniformity with sample MB2-6 varying approximately +/−2.5 micron from the average diameter of 6.39 micron (Table 1-4).

TABLE 1-4

Electron Microscope Fiber Diameter Measurements

	MB2-3	MB2-6

10 fibers were selected at random	10.01	8.89
from each Sample fabric	9.19	7.76
	7.93	4.51
	5.05	5.59
	7.62	6.18
	7.61	6.89
	8.1	5.59
	9.33	6.94
	9.08	4.82
	9.33	6.74
average fiber diameter (microns)	8.33	6.39

It is important to note that the melt index of the improved EFEP RP-5000 polymer used in Example #3 was well below 100. High quality nonwovens were produced, with fiber diameters below 7 microns, with low airflow resistance (Table 1-5). Nonwoven samples MB2-3 and MB2-6 also had with good first pass collection efficiencies over a wide range of particle sizes using an ASHRAE 52.2 test method (Table 1-6). It is important to note that the collection efficiencies method by which samples MB2-3 and MB2-6 were evaluated was using a modified ASHRAE 52.2 procedure that tested only for initial collection efficiency without the benefits of accumulated dust cake loadings. It is well know to those skilled in the art that the dust cake loading build up of previous exposures to dirt, or particles in filter testing often substantially increases overall collection efficiency ratings of filters. In many cases collection efficiencies of first pass tests, like those detailed in table 1-6, will double or exponentially improve collection of particles as the “seasoning” process of previous captured dirt blocks filter passages and renders the filter more efficient, as well as increasing pressure drop or resistance to airflow.

TABLE 1-5

						Re-
						sist-
						ance
		% of	Resistance	Resistance	Resistance	“H2O
Velocity	Airflow	test	PA	“H2O	PA	Filter
FPM	CFM	airflow	Filter 2-6	Filter 2-6	Filter 2-3	2-3

500	125	100	186.75	0.75	174.3	0.7
625	156.25	125	224.1	0.9	191.73	0.77
750	187.5	150	286.35	1.15	244.02	0.98

	TABLE 1-6

	Range Number

	1	2	3	4	5	6	7	8	9	10	11	12

Size Range, μm	0.30–0.40	0.40–0.55	0.55–0.70	0.70–1.00	1.00–1.30	1.30–1.60	1.60–2.20	2.20–3.00	3.00–4.00	4.00–5.50	5.50–	7.00–
											7.00	10.00
Geometric	0.35	0.47	0.62	0.84	1.14	1.44	1.88	2.57	3.46	4.69	6.20	8.37
Mean Particle
Size, μm
Initial 1 (2-6)	24.3	34.8	48.7	54.1	52.3	49.6	45.8	45.1	38.8	33.3	32.7	32.6
Initial 2 (2-6)	23.0	35.2	51.3	57.9	57.2	54.4	51.7	49.2	43.7	42.2	43.2	40.5
Initial 3 (2-6)	23.5	34.0	49.7	56.4	56.1	53.0	50.7	48.4	41.9	37.5	37.9	40.2
Initial 4 (2-3)	17.8	29.0	38.8	42.5	38.9	35.4	32.4	32.4	28.0	24.6	27.4	25.3
Initial 5 (2-3)	21.8	31.4	42.4	46.9	45.6	42.4	39.8	38.4	33.3	27.3	30.5	22.7
Initial 6 (2-3)	20.9	30.4	40.0	42.8	40.0	36.6	34.9	34.9	29.7	28.5	31.1	29.9
Composite	23.6	34.7	49.9	56.1	55.2	52.3	49.4	47.6	41.5	37.7	37.9	37.8
Average (2-6)
Composite	20.2	30.3	40.4	44.1	41.5	38.1	35.7	35.2	30.3	26.8	29.7	26.0
Average (2-3)

The melt index (MI) referred to herein refers the number of grams of the material that can be forced through the ASTM recommended orifice in 10 minutes using the ASTM recommended temperature and pressure (i.e., using ASTM standards for the material). The melt indices (MI) of the fluorine containing copolymers disclosed herein are preferably below 100 as indicated above (e.g. about 35 or about 78).
As used herein, the following directional terms “forward, rearward, above, downward, vertical, horizontal, below and transverse” as well as any other similar directional terms refer to those directions of a device equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a device equipped with the present invention.
The term “configured” as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function.
Moreover, terms that are expressed as “means-plus function” in the claims should include any structure that can be utilized to carry out the function of that part of the present invention.
The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.
While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. Thus, the scope of the invention is not limited to the disclosed embodiments.

Claims

1. A non-hollow, monofilament fiber consisting essentially of a fluorine containing copolymer having a melt index (MI) of less than 100.

2. The non-hollow fiber as set forth in claim 1, wherein

the fluorine containing copolymer has a melting point below 240° C.

3. The non-hollow fiber as set forth in claim 2, wherein

the fluorine containing copolymer has a melting point below 200° C.

4. The non-hollow fiber as set forth in claim 1, wherein

the fluorine containing copolymer is a fluorine-containing ethylenic polymer (A) represented by the general formula

where l, m, and n are natural numbers and X and Y are functional groups.

5. The non-hollow fiber as set forth in claim 4, wherein

the functional groups X and Y are carboxyl groups.

6. The non-hollow fiber as set forth in claim 4, wherein

at least one of the functional groups X and Y includes at least one of a carbonate group and a carboxyl halide group.

7. The non-hollow fiber as set forth in claim 6, wherein

the functional groups X and Y include a carbonate group and a carboxyl halide group.

8. The non-hollow fiber as set forth in claim 7, wherein

the carbonate group is represented by the formula:

—OC(═O)O—R

wherein R is one of the group consisting of a hydrogen atom; an alkyl group with 1-20 carbon atoms; an alkyl group with 2-20 carbon atoms and an ether coupling; and an element of the first, second, or the seventh group.

9. The non-hollow fiber as set forth in claim 1, wherein

the fiber is a staple fiber.

10. The non-hollow fiber as set forth in claim 1, wherein

the fiber is a filament fiber.

11. A fabric comprising:

non-hollow, monofilament fibers consisting essentially of a fluorine containing copolymer having a melt index (MI) less than 100.

12. The fabric as set forth in claim 11, wherein

the fluorine containing copolymer has a melting point below than 240° C.

13. The fabric as set forth in claim 112, wherein

the fluorine containing copolymer has a melting point below than 200° C.

14. The fabric as set forth in claim 11, wherein

where l, m, and n are natural numbers and X and Y are functional groups.

15. The fabric as set forth in claim 14, wherein

the functional groups X and Y are carboxyl groups.

16. The fabric as set forth in claim 14, wherein

17. The fabric as set forth in claim 16, wherein

18. The fabric as set forth in claim 17, wherein

the carbonate group is represented by the formula:

—OC(═O)O—R

19. The fabric as set forth in claim 11, wherein

the fabric is a woven fabric.

20. The fabric as set forth in claim 11, further comprising

a non-fluoropolymer material.

21. The fabric as set forth in claim 20, wherein

the fibers consisting essentially of the fluorine containing copolymer are at least partially disposed at an outer surface of the fabric.

22. The fabric as set forth in claim 20, wherein

the fabric is a non-woven fabric.

23. The fabric as set forth in claim 11, wherein

the fabric is a non-woven fabric.

24. The fabric as set forth in claim 23, wherein

the fibers consisting essentially of the fluorine containing copolymer are melt-blown fibers.

25. The fabric as set forth in claim 24, wherein

the fibers consisting essentially of the fluorine containing copolymer have a melting point below 240° C.

26. The fabric as set forth in claim 25, wherein

the fibers consisting essentially of a fluorine containing copolymer have a melting point below 200° C.

27. The fabric as set forth in claim 24, further comprising

a non-fluoropolymer material.

28. The fabric as set forth in claim 27, wherein

the fabric includes a plurality of fibers consisting essentially of the non-fluoropolymer material.

29. The fabric as set forth in claim 23, wherein

the fluorine containing copolymer is represented by the general formula

where l, m, and n are natural numbers and X and Y are functional groups.

30. The fabric as set forth in claim 11, wherein

all fibers of the fabric consist essentially of the fluorine containing copolymer.

31. A fiber containing EFEP.

32. The fiber as set forth in claim 31, wherein

the fiber is a non-hollow fiber.

33. The fiber as set forth in claim 32, wherein

the fiber is a monofilament fiber consisting essentially of EFEP.

34. A fabric containing EFEP.

35. The fiber as set forth in claim 34, wherein

the fabric includes fibers containing EFEP.

36. The fiber as set forth in claim 35, wherein

the fibers are non-hollow fibers.

37. The fiber as set forth in claim 36, wherein

the fibers are monofilament fibers consisting essentially of EFEP.

38. The fiber as set forth in claim 35, wherein

the fibers containing EFEP are melt blown fibers.