CA2077100A1

CA2077100A1 - Grease-absorbent microwave cooking pad and package

Info

Publication number: CA2077100A1
Application number: CA002077100A
Authority: CA
Inventors: Gary A. Isakson; Pierre H. Lepere; Daniel Meyer; James R. Nelson
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1991-09-30
Filing date: 1992-08-28
Publication date: 1993-03-31
Also published as: JPH05280753A; EP0535451A1

Abstract

GREASE-ABSORBENT MICROWAVE COOKING PAD AND PACKAGE
ABSTRACT OF THE DISCLOSURE
A pad for use in the cooking of food placed thereon in a microwave oven is disclosed. The pad is specifically designed for use in connection with food, (e.g., bacon strips) that contains a substantial amount of solidified grease which melts when the food is cooked by microwave radiation. The pad is formed from an entangled web formed from at least one generally hydrophobic and grease absorbing multilayer microfiber.
The web is formed by combining at least two streams of flowable polymer materials (e.g., polypropylene and polyethylene terephthlate) in a layered, combined flowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruding flowstream with a high velocity gaseous stream to form fiber, and collecting the fiber on a collective surface so as to form the entangled web. A
pad so formed is capable of holding the amount of grease in the food placed thereon when the grease is heated by cooking the food in a microwave oven.

A:946-7A.CAN

Description

~ 1 --4 694 6CAI`17A

~E-A13~0RBENT MICROWAV13 COOKING PAD AND PACKAGE

BACKGROUND OF_THF INVENTION

This invention relates to a grease-absorbent pad f or use in the microwave oven cooking o~ food that contains a large amount of solidified yrease a~d water, 10 and to a package with such a pad and such food sealed therein for cooking purposes.
Foods, particularly precooked and cured foods such as bacon, sausage, ham, or bologna, that contain a large amount of water and solidified grease can cause 15 problems when cooked in a microwave oven. Water in such foods is vaporized by contact with the heated melting grease as the food cooks, causing tiny explosions that can splatter portions of the grease around the oven. In addition, the solidified grease 20 melts when the food is cooked by microwave radiation~
one attempt to address those concerns has been to place the food on a pan that collects the melted grease, and to cover the food with several layers of paper towels to restrict splattering.
It is known to place a liquid absorbent pad within a package for absorbing ~ood by-products such as moisture and grease exuded from food during cooking in a microwave oven. Such pads must not only sufficiently absorb the quantity of food by-products produced during 30 cooking, but must also withstand the elevated temperatures required to adequately cook th~ precooked or cured foods without degradation.
HoweYer, conventional absorbent pads absorb both water and various greases from the food. This is 35 undesirable in that if part of the absorbent capacity of the pad is occupied by moisture, insufficient capacity may :remain for grease. Alternatively, the 2 - 2~77~ ~
capacity of the pad must be increased by increasing the size and weight of the pad, at additional expense.
It is also desirable in many cases for water exuded from a food in the form of steam during cooking 5 to be maintained in the close proximity to the food to evenly distribute heat within t:he package and to reduce the cooking time for the food. An additional problem occurs during extended storage and transportation of a package containing the food having substantial amounts 10 of water and grease. A pad that absorbs water as well as grease will tend to gradually absorb water from the food. Thus, a subsequent measurement may show that the weight of the food has been reduced compared to the weight at the time the package was sealed.
One attempt to address these concerns is presented in Larson U.S. Patent 4,865,854, which discloses a microwave oven food package for use in cooking food containing a substantial amount of water and solidified grease. The package includes a pad 20 adjacent the food which is formed from microwave radiation transparent and generally hydrophobic grease-absorbing microfibers which are capable of holding the amount of grease in the food when it is melted. The package ~urther includes a vapor-tight micrswave 25 radiation transparent enclosure surrounding the pad and food that has a steam ven~ which opens as the food is cooked. This patent teaches producing the pad for this package from blown microfibers ~BMF) made in accordance with the teachings oP U.S. Patent Nos. 4,103,058 and 30 4,042,740.
A pad formed as disclosed in khe Larson patent discussed above, while having, its own utility, has proved to be relakively expensive for commercial microwave food packaging purposes. Such a pad has been 35 made by melt-blown microfibers formed into an entangled web. Polymer pellets were dry blended together to form a 50/50 mixture of polypropylene and poly 4-~, $~ '~ 7 ~

methylpentene-1 (a relatively expensive polymer~.
Polypropylene and poly 4-methylpentene--1 can be dry blended and extruded to a usable product.
It is desired to develop a pad for use in a 5 microwav2 oven packaye which has an increased grease absorbency, thus reducing the pad size or thickness requirements and hence lowering the pad weight, as well as lowering production costs and material expenses. In some applications, it is also desirable to bond a scrim lO or cover sheet of a separate material to the pad on its food adjacent surface, and a pad is sought which will readily maintain such a bond. In addition, it has been desired to develop grease-absorbent pads for microwave food packages from blends of polymer materials which 15 were previously unblendable in conventional extrusion techniques to produca a satisfactorily blended microfiber and finished pad product for commercial applications, yet attaining increased absorbency and bonding charactaristics.
_UMMARY OF THE INVENTION
The present invention provides a grease-absorbent pad for use such as in a package for ~ood containing a substantial amount of water and solidified 25 grease that is to be cooked in a microwave oven. The pad is formed from an entangled web of generally hydrophobic and grease-absorbing multi-layer microfibers. The web is prepared by combining at least two streams of flowable materials in a layered, 30 combined ~lowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruded flowstream with a high velocity gaseous stream to form fibers and collecting the fibers on a collective surface so as to form the entangled web.
- 35 This pad is capable of holding the amount of grease in the food when the grease is melted by cooking the food in a microwave oven.

.~

~7~ a In one embodiment, the pad i~ used in combination with a microwave food cooking package. The package prevents splattering of the grease onto the inside of the microwave oven, collects the grease 5 during the cooking process, does not require special handling to preclude spilling the collected grease after the substance or food has been cooked, and is easy to manufacture. According to the present invention, a package for use in a microwave oven 10 includes foods, and in particular, precooked or cured foods containing a substantial amount of water and solidified grease (e.g., bacon, sausaye., ham, or bologna); a pad adjacent the food comprising an entangled web of generally hydrophobic and grease 15 absorbing multi-layer microfibers, formed as described above; and a vapor-tight microwave radiation transparent enclosure surrounding said pad and said food.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further described with reference to the accompanying drawings wherein:
FIG. 1 is a perspective view of a microwave food package according to the present invention.
FIG. 2 is an enlarged fragmentary sectional view of the package shown in FIG. 1.
FIG. 3 is an enlarged fragmen-tary view of the package of FIG. 1 while food therein is being cooked in a microwave oven.
FIG. 4 is a perspective view of the package of FIG. l being opened.
FIG. 5 is an ~nlarged fragmentary sectional view of a food cooking pad with food thereon of the present invention.
FIG. 6 is a schematic representation of an apparatus useful for producing a nonwoven web of longitudinally layered melt-blown microfibers to define - 5 - 2~
a pad useEul tn cooking ~ood in a microwave oven.
Fl(,. '1 ig an electron micrograph cross sectlon o:~ bl~ncle~ fiber~ of polypropylene ~PP) ~nd polymethylpentene (T~X), blended by a "dry-blend"
5 technique of the prior art.
FIGS. 8 and 9 are scanning electron micrograph cross sections multi-layer blended ~ibers o~
polypropylene ~pp) and polyethylene terephthalate (PET), blended by the web ~ormation process described 10 herein.
It is understood that the drawing figures herein are provided ~or illustrative purposes only and are not drawn to scale, nor should they be construed to limit the intended scope and purpose o~ the present 15 invention.

DETAILED DESCRIPTION OF THE PREFERRED_EMBODIM NTS
The Inventive Package and Web _ructures FIGS. 1-4 show a package of ~ood according to 20 the present invention that can be cooked in a microwave oven, with the package being generally designated by reference numeral 10. As best seen in FIGS. 1 and 2, the package 10 includes food (e.g., strips of bacon) 12 containing wa~er and a substantial amount o~ solidified 25 grease, and a pad 14 adjacent the food 12. The pad 14 is formed from a microwaYe radiation transparent generally hydrophobic grease-absorbing material which is capable of at least absorbing the amount of grease in the food 12 when that grease is li~uefied.
30 Preferably, the pad comprises coextruded multi-layer blown microfibers, made in accordance with the web formation process described herein.
A generally rectangular vapor-tight microwave radiation transparent enclosure 16 surrounds the pad 14 35 and food 12 and comprises top and bottom rectangular sheets 17 and 18 o~ polymeric film fastened together as by heat sealing to provide a vapor-tight seal 19 around - 6 ~ 3~
their peripheries, with the pad 14 and, ~ood 12 therebetween. Suit~ble msans may be provided for venting the enclosure 16 to facilitate cooking th~ food 12 within the enclosl~re 16 in a microwave oven. In one 5 embodiment, as shown, the means for venting comprises a layer of microwave radiation absorbable material in the form of a piece of metal vapor coated film 20 adhered by a suitable adhesive to the top sheet 17 of the polymeric film forming the enclosure 16. The vapor 10 coated film 20 and a portion of the top sheet 17 adjacent thereto will be softened by heating of the metal vapor coating to cause rupture of that top sheet 17 of film and vapor coated ~ilm 20 due to steam or vapor pressure within the enclosure 16 and/or different 15 amounts of shrinking of the films 17 and 20 during cooking of the food 12 by microwave energy. As illustrated in FIG. 3, the top sheet 17 of film and the vapor coated film 20 will thus allow èxcess steam or vapor pressure within the enclosure 16 to escape, while 20 retaining sufficient steam or vapor within the enclosure 16 to enhance cooking of the food 12. In anothar embodiment, the means for venting is a weakened portion of the heat seal between a portion of the periphery of the enclosure, which is ruptured lin a 25 controlled manner) by the buildup of steam or vapor pressure within the enclosure when the food is cooked, thereby regulating the cooking of the food and pressure within the enclosure.
The package lO also has an arrangement for 30 affording easy manual opening of the enclosure 16 to facilitate removal of the cooked food 12. A portion of the seal 19 between the face-to-face layers of the polymeric film adjacent one edge 24 or corner area of the package :L0 is spaced a substantial distance (i.e., 35 over 3 cm. and preferably about 6 cm.) from that edge 24 and is adapted to be peeled apart by manually pulling apart the top and bottom sheets 17 and 18 of - 7 ~ '7 ~ t~ ~
the film adjacent the ~dge 24. rrhls oE~eniny can occur without compressing the packaye 10 50 that hot vapors will not be forced ~rom within the package 10 through the vents formed at the vapor coated film 20 as the 5 package is apened.
PrefPrably, the pad ma~erial :Ls selected to have about the same surface ar~a as the food which is supported on the pad. Accordingly, the pad can so completely absorb or otherwise hold all of the yrease 10 contained in that food (after the food is cooked and removed from the enclosure) that the enclosure and pad therein will not drip grease even when the openiny through which the food was removed is lowermo~t on the enclosure. Pads which can hold in the range of at 15 least 1 to 2 grams of grease per sq/in. of sur~ace area have been found suitable for packaging conventional bacon strips~ FIG. 2 illustrates a pad se]ected to be about the same size and surface area as the food thereon. During cooking, some ~ood products shrink in 20 size (e.g., bacon strips). FIG. 5 illustrates a pad 14a of reduced surface area size relative to the food 12a placed thereon. The pad l~a may be smaller in surface area than the food 12a thereon, so long as it is sufficient in absorbency of grease to absorb all - 25 liquefied grease during cooking of the food 12a. To compensate for a smaller surface area, such a pad may need to be thicker.
Although in one preferred embodiment the pad 14 is designed for use within an enclosure 16 to form a 30 package 10 such as illustrated in FI&S. 1-4, it is also contemplated that such a generally hydrophobic and oleophilic pad may be used alone in a microwave oven for food cooking purposes. AS such, the food i5 placed upon the pad, with no preformed, vapor-tiyht enclosure 35 thereabout. The pad and food may then be retained within a pan or container (e.g., repre~ented by reference numeral 26 in FIG. 5) for holding the 2 ~ f3 li~ue~`ied grease as the food is cooked and for handling the ~ood once cooked. The container may or may not ~urther include a lld or cover (e.g., as represented by raference numer~l 28 in FIG. 5) to contain ~ood 5 splatteriny during the cooking process.
The Web Fo~ n_ELQ~Q~
AS mentioned, the pad is formed from blown microfibers produced by a process which, in part, u~es the apparatus discussed, for example, in Wente, Van A., 10 "Superfine Thermoplastic Fibers, " ~Lstria1 Enqineering Chemlstr~, Vol. 48l pp 1342-1346 and in Wente, Van A. et al., "Manufacture O:e Super~ine Oryanic Fibers," Report No. 4364 o~ the Naval Research Laboratories, published May 25, 1954, and U.S. Pat.
15 Nos. 3,849,241 (Butin et al.), 3,825,379 (Lohkamp et al.), 4,818,463 (Buehning), 4,986,743 (Buehning), 4,295,809 (Mikami et al.) or, 4,375,718 (Wadsworth et al.). These apparatuses and mPthods are useful in the invention procPss in the portion shown 20 schematically as die 40 in Fig. 6, which could be of any of these conventional desiyns.
Each microfiber is formed ~rom two or more separate polymer material components. The polymeric components are introduced into the die cavity 42 of die 25 40 from a separate splitter, splitter region or combining manifold 30, and into the, e.g., splittsr from extruders, such as 32 and 34. Gear pumps and/or purgeblocks can also be used to finely control the polymer flow rate. In the splitter or combining 30 manifold, the separate polymeric component flow streams are formed into a single layered flowstream. However, preferably, the separake ~lowstreams are kept out of direct contact for ~s long a period as possible prior to reaching the die 40. The separate polymeric 35 flowstreams from the extruder(s) can also be split in the splitter ~30). The split or separate flowstreams are combined only immediately prior to reaching the 7 7 ~
die, or dle orl~ic~s. ThLs m:inimizes the possibility of flow instabilities generating in the separate flowstreams after being comblned in the sinyle layered flowstream, which tends to result in non-uniform and 5 discontinuous longitudinal layers in the multi-layered microfibers. Flow instabilities can also have adverse effects on nonwoven web propert:ies æuch as strength, temperature stability, or other desirable properties obtainable with the invention E)rocess.
ThP separate flowstreams are preferably established into laminar flowstreams along closely parallel flowpaths. The flowstreams are then preferably combine.d so that at the point of combinat:ion, the individual flows are laminar, and the 15 flowpaths are substantially parallel to each other and the flowpath of the resultant combined layared flowstream. This again minimizes turbulence and lateral flow instabilities of the separate ~lowstreams in and after the combining process. It has been found 20 that a suitable splitter, ~or the above described step of combining separate flowstreams, is one such as is disclosed, for example, in U.S. Pat. No. 3,557,265, which describes a manifold that forms two or three polymeric components into a multi-layered rectilinear 25 melt flow. The polvmer flowstreams from separate ; extruders are fed into plenums and then to one of the three available series of ports or orifices. Each series of ports is in fluid communication with one of the plenums. Each stream is thus split into a 30 plurality of separated flowstreams by one of the series of ports, each with a height-to-width ratio of from about 0.01 to 1. The separated flowstreams, from each of the three plenum chambers, are then simultaneously coextruded bv the three series of ports into a single 35 channel in an interlacing manner to provide a multi-layered flowstream. The combined, multi-layered flowstream in the channel is then transformed (e.g., in ~7;~
-- 10 ~
a coathanger transit:ion p.iece), so that each layer extruded from the mani~old ori~ices has a substantially smallar height-to-w.idth ratio to provide a layered combin~d flowstream at the die ori~ice~; with an overall 5 height of about 50 mils or less, preferably 15-30 mils or less~ Other suitable devices Eor providing a multi-layer flowstream are such as disclosed in U.S. Patents Nos. 3,924,990 ~Schrenk); 3,687,589 (Schrenk) 3,759,647 (Schrenk et al.) or 4,197,069 (Cloeren), all of which, 10 except Clo~ren, disclose mani~olds ~or bringing together diverse polymeric flowstreams into a single, : multi-layer flowstream that is ordinarily sent through a coat hanger transition piece or neck-down zone prior to the f.ilm die outlet. The Cloeren arrangement has 15 separate ~low channels in the die cavity. Each flow channel is provided with a back-pressure cavity and a flow-restriction cavity, in successive order, each preferably defined by an adjustable vane. The adjustable vane arrangement permits minute adjustments 20 of the relative layer thicknesses in the combined multi-layered flowstream. The multi-layer polymer flowstream from this arrangement need not necessarily be transformed to khe appropriate length/width ratio, as this can be dons by the vanes, and the combined 25 flowstream can be fed directly into the die cavity 42.
The multi-layer polymer flowstream is normally fed into the die cavity 42 as an integral flow. However, it is possible to keep the layer flowstreams separate in the diP cavity 42 by use of 30 separator plates that would allow the separate polymer flowstreams to combine immediately prior to reaching the die orifices.
From the die cavity 42, ths multi-layer polymer flowstream is extruded through an array of 35 side-by-side orifices 41. As discussed above, prior to this extrusion, the fPed can be formed into the appropriate pro*ile in the cavity 42, suitably by use 2 ~ 7 ~ , i3 ~

of a conventional coathanger transitlon piece. Air slots 48, or the llke, are disposed on elther side of the row of orifices ~1 for directing uniform heated air at high velocity at the extruded layered melt streams.
5 The alr temperature is generally about that of the melt stream, although preferably 20--30c higher than the melt temperature. This hot, high-velocity air draws out and attenuates the extruded polymeric material, which will generally solidify after traveling a 10 relatively short distance from the die 40. The solidified or partially solidii-ied fibers are then formed into a web by known methods and collected on a collector surface 49, such as rotating drum 50. The collecting surface can be a solid or perforated surface 15 in the form of a drum (as shown), or a flat sur~ace, a moving belt, or the like. If a perforated surface is used, the hackside of the collecting surface can be exposed ko a vacuum or low-pressure region to assist in the deposition of fibers, such as is disclosed in U.S.
20 Pat. No. 4,103,058 (Humlicek). This low-pressure region allows one to form webs with pillowed low~
density regions. The collector distance can generally be from 3 to 50 inches from the die face. With closer placement of the collector, the fibers are collected 25 when they have more velocity and are more likely to have residue tackiness from incomplete cooling. This is particularly true for inherently more tacky thermoplastic materials, such as thermoplastic elastomeric materials. Moving the collector closer to 30 the die face, e.g., 3 to 12 inches, will result in stronger inter-fiber bonding and a less lofty web.
Moving the collector back (e.g., 20 inches) will generally tend to yield a loftier and less coherent web.
The temperature of the polymers in the splitter region is generally about the temperature of the higher melting point component as it exits its 2~7r~1~0 extruder. The splitter region or manifold is typically inteyral with th~ die and is kept at the same temperature. ~he temperature of the. separate polymer flowstreams can also be controlled to bring the 5 polymers closer to a more suitable relative viscosity.
When the separate polymer flowstreams converge, they should generally have an apparent viscosity of ~rom 150 to 800 poise, preferably from 200 to 400 poise (as measured by a capillary rheometer). The relative 10 viscosities of the separate polymeric flowstreams to be converged should generally be fairly well matched.
Empirically, this can be determined by varying the temperature of the melt and observing the crossweb properties o~ the collected web. The more uniform the 15 crossweb proparties, the better the viscosity match.
The overall viscosity o the layered combined polymeric flowstream(s) at the die face should be from 150 to 800 poise. The differences in relative viscosities are preferably generally the same as when the polymeric 20 flowstreams are first combined. The apparent viscosities of the polymeric flowstream~s) can be adjusted at this point by varying the temperatures as per U.S. Pat. No. 3,849,241.
The size of the polymeric fibers formed 25 depends to a large extent on the ~elocity and temperature of the attenuating airstream, the orifice diameter, the temperature of the melt stream, and the overall flow rate per orifice. At high air volume rates, the fibers formed have an average fiber diamet~r 30 of less than about 10 micrometers, however, there is an increased difficulty in obtaining webs having uniform properties as the air flow rate increases. At more moderate air flow rates, the polymers have larger average diameters, however, with an increasing tendency 35 for the fibers to entwin~ into formations called "xopes'l. Thi~ is dependent on the polymer flow rates, of course, wit:h polymer flow rates in the range of 0.05 to 0.5 cjm/min/orifice generally being sui.table.
coarser fibers, e.g., up to 25 micrometers or more, can be used in certain circumstances such a8 large pore or coarse wehs.
The multi~layer microfibers ~ormed by this process can be admixed with other fibers or particulates prior to beiny co:llected. For example, sorbent particulate matter or fibers can be incorporated into the coherent web of blown multi~
10 layered fibers as diæcussed in U.S. Pat. Mo~. 3,971,373 or 4,429,001. In these patents, two separate streams of melt-blown fibers are estab:Lished with the streams intersecting prior to collection oE the fibers. The particulates, or f:ibers,, are entrained into an 15 airstream, and this particulate laden airstream is then directed at the intersection point of the two microfiber streams other methods of incorporatiny particulates or fibers, such as staple fibers, bulking fibers or binding fibers, can be u~ed with the 20 invention method of forming melt-blown microfiber webs, such as is disclosed, for example/ in U.S. Pat. Nos.
4,118,531, 4,429,001 or 4,755,178, where particles or fibers are delivered into a single stream of melt-blown fibers.
Other materials such as surfactants or binders can be incorporated into the web before, during or after its collection, such as by use of a spray jet.
if applied before collection, the material is sprayed on the stream of microfibers, with or without added 30 fibers or particles, traveling to the collection surface.
The inventive web formation process and microfibers formed thereby also forms the basis for the following patent applications, all filed on the same 35 date as this application:
(1) Novel Material and Material Properties From Multi-Layer Blown Microfibers;

2 ~ P~

(2) Stretchable Nonwoven Webs Based on Multi-Layer Blown Microfi~er;
(3) Improved Modulus Nonwoven Webs Based on Multi~Layer Blown Microfibers;
(4) High Tsmperature Stable Nonwoven Webs Based on Multi-Layer Blown ~icrofibers;
(5) Film Materials Based on Multi-Layer Blown Microfibers; and (6) Wipe Materials ~ased on Multi-Layer lO Blown Micro~ibers; and all o~ which are incorporated by reference.
The microfiber formation process described provides webs having unique properties and characteristics when compared to webs ~ormed ~rom a 15 homogeneous polymer melt, of a single polymer or blends of polymers (compatible or incompatible). For example, FIG. 7 illustrates an electron micrograph praparation of a 50/50 blend of polypropylene (PP) and polymethylpentene (TPX). These polymers were "dry 2~ blended" together in pellet form, prior to extrusion.
In other words, the polymers were blended and then ; forced through a single extrusion orifice in a conventional dry-blend ~xtrusion process. The extruded fi~r was ~ormed into a web as described above on a 25 collector.
To form the illustration of FIG. 7, samples of the blown microfiber were first stained with a solution having 0.2 grams of RuCl3:H30 powder dissolved in lO ml. of 5.25 aqueous sodium hypochlorite. Each 30 sample was soaked in this solution ~or two to two and one-half hours at room temperature (about 20C). Each sample was then removed, rinsed with deionized water and air dried on filter paper for 24 hours. Each sample was then embedded into "Scotch Cast" brand 35 electrical resin No. 5 available from the Minnesota Mining and Manufacturing Company, using embedding molds for microtomy, and the resin was cured for 24 hours at 15 - 2 ~
room temperature. Thin sections, approximate]y 0.1 micrometer thick were cut from the sample with a diamond knife on a Reichert Ultracut E/F D-4 cryoultramicrotome at a temperature between -45C to -s soc. Each section was then picked up on a carbon-saturated grid and brought to ~oom temperature be~ore examining with a JEOL 100 cX transmission electron microscope operated at 100 kV. The dark portions in the electron photomicrograph of FIG. 7 is the stained 10 polymethylpentene, which can be seen to be randomly distributed in the fiber. This results in a fiber having nonuniform strength, blending and bondiny characteristics, as can be readily appreciated by viewing FIG. 7.
As long as the viscosities of th~ particular polymers are suitably matched, it is possible to form generally uniform multi-layered microfibers ~rom two tor more) polymers which otherwise may be incompatible (e.g., polypropylene and polyethylene terephthalate).
20 It is thus possible to obtain microfiber nonwoven webs having certain desired characteristics which would otherwise not be obtainable from these otherwise incompatible polymers used individuallyO For example, a blown microfiber pad of 100 percent polyethylene 25 terephthalate (PET) heated to 350F will shrink excessively, and a blown microfiber pad of 100 percent polypropylene (PP) heated to 350F will show visible melting. However, a blown microfiber pad formed by the microfiber formation process descrihed herein which i~
30 a 50/50 coextrusion of polyethylene terephthalate and polypropylene heated to 350~F shows no visible signs of melting and no perceptible shrinking. The addition of any amount of a high temperature stable polymer (e.g., PET) improves the desired properties of the bonding 35 polymex (e.g., PP~ in such a blown microfiber pad of coextruded microfibers. A combined flowstream of such polymers, with one of the polymers constituting between - 16 - 21)7~
20 to 80 percent by weight of the flow~tream, results in ~ usable web p~oduct, although a preferred composition would have one of the polymers constituting betwe~n 40 to 60 percent of the flowstream.
Surprisingly, the overall web properties of these novel webs formed from multi-layered microfiber webs are generally unlike the web properties of homogeneous webs formed o~ any of the component materials. In ~act, the multi--layered microfibers 10 frequently provide completely novel web properties and/or ranges of properties not obtainable with any o~
the component polymer materials. Eor example, Piber and web modulus can be controlled within wide ranges for given combinations of polymers by varying, 15 indepenflently, the relative ratios of the polymers, the layer order in the microfibers, the number o~ layers, the collector distance and other process variables.
The web formation process thus allows precise control of such properties as web modulus and absorbency by 20 varying one or all of these variables.
In forming a web which is grease absorbent and suitable for microwave cooking o~ food, it is necessary that ths web microfibers be temperature stable at the temperature levels re~uired for cooking 25 foods by microwave radiation. The microfibers in the inventive heat stable melt-blown web arP formed ~rom a combination of at least two distinct layer types. The first layer type comprises a heat-stable melt-blowable material which is used in combination with a second 30 layer type o~ a relatively non heat-stable but comparably yood web-forming layer material.
The relatively heat-stable material can be any heat-stable ~a high melting point polymer3 polymeric material capable of being melt-blown. These 35 materials are generally highly crystalline and have a high melting point. However, a problem with these materials is that they exhibit a relatively low degree 2 ~
- 17 ~
of ~elf-bond~ng. Self-bondiny reEers to the ability of the individual ~ibers to bond to each other when collected on a aollecting surface from the melt-blowing die. These heat stable materials as such form low-5 strength webs generally lacking the integrity requiredfor most typical applications of melt-blown web products unless post-embossed.
Typical examples of such heat-stable materials include polyesters such as polyethylene 10 terephthalate, polyolefins such as poly 4-methyl-1-pentene or a polyallylene sulfide such as poly(phenylene sul~ide). Such materials exhibit relatively high individual fiber ~trength, yet exceedingly low interfiber bonding, and as such form 15 generally low-strength webs even at relatively close collector to die distances. Generally, these materials are characterized as melt-blowable polymers having glass transition points above room temperature or melt temperature of greater than 180C, and preferably 20 greater than 150C. Prefarably, the heat-stahle polymers can produce webs that are stable at temperatures above about 130C, more pre~erably above 150C.
The second layer material used in the 25 inventive microfibers and web is generally a material exhibiting significantly higher sslf-bonding characteristics at melt blowing conditions. Typically the6e materials will exhibit a softening or melting temperature approximately 30C below that of the high 30 modulus material, but preferably within 150C of the high modulus material melting point. Too large a difference in melting points can render the polymers difficult to coextrude. Generally, the self-bonding component will have a glass transition temperature 35 below room temperature, preferably below about 15C.
The preferred materials will be amorphous or semicrystalline materials exhibiting relatively good !2 ~ ~' 7 l ~ ~
bonding char~cteristics at melt-blowing con~itions.
Suitable materials include polyolePins such as polypropylene. The materials comprising the relatively high-bondinq layer material can also include 5 conventional additives.
By using relatively low levels (e.g., ~50%) of the relatively heat-stable material in combination with the second layer material, as defined herein, the mechanical per~ormance characteristics of the 10 relatively heat-stable material can be obtained. The web will also exhibit the desirable characteristics of the second layer material at lower temperatures.
The heat-stable webs formed o~ the above describad multi-layer microfibers have relatively hiyh 15 strength properties over an extended temperature ranye.
Fiber and web modulus is further controllable within wide ranges ~or given combinations of polymers by varying, independently, the relative ratios of the polymers, the layer order in the microfibers, the 20 number o~ layers, the collector distance and other process variables. The invention thus allows precise control o~ web strength by varyiny one or all of these variables~
At least a portion of the high-bonding 25 component is preferably at the fiber surface. The heat-stable layer stabilizes the bonding component layer while the bonding component material at the surface provides interfiber bonding. Theoretically, the relative volume percent of the individual layers 30 can vary widely, for example, from 1 to 99 volume percent for each individual layer component. The preferred amount of the individual layer components will depend upon the relative amount of modulus desired with the individual high-temperature web and the 35 desired high temperature performance required.
Generally, th,e outside layers will contribute significantly to the surface properties forming at the C~, ~3 ~

web without significantly modifyiny the bulk fiber properties, such as tensilc strenyth and modulus behavior when used at a relatively low~volume percent.
In this manner, the relatively high-bonding materials 5 can be used as thin outer layers to contribute to web properties without significantly affecting the bulk fiber properties.
With the web ~ormation process described herein, the web properties are further altered by lO variations in the number of layers employed at a given relative volume percent and layer arrangement. As described above, variation in the number o~ layers, at least at a low number of layers, has a tendency to significantly vary the relative . proportion of each 15 polymer (assuming two polymeric materials) at the microfiber surface. This (assuming alternating layers of two polymeric materials) translates into variation of those web properties to which the micro~iber surface properties significantly contribute. Thus, web 20 properties can change depending on what polymer or composition comprises the outside layer(s~ . However, as the number of layers increases, this variation in web properties based on surface area effects diminishes. At higher-layer numbers, the relative 25 thicknesses of the individual fiber layers will tend to decrease, significantly decreasing the surface area effect of any individual layer. Pre~erably, the melt-blown microfibers have average diameters of less than 20 micrometers.
The number of layers obtainable with the ; process described is theoretically unlimited.
Practically, the manufacture of a manifold, or the like, capable of splitting and/or combining multiple polymer streams into a very highly layered arrangement 35 would be prohibltively complicated and expensive.
Additionally, in order to obtain a flowstream of suitable dimensions for feeding to the die orifices, ?~ r3 ~ rl ~
- 20 ~
forming and then maintaining l~yering through a suitable transition plece can become di~ficult. A
practical limit o~ 1,000 layers is contemplated, at which point the proc~ssing problems would likely 5 outweigh any potential added property benefits.
The webs formed can be of any suitable thickness for the desired end u.se. However, generally a thickness from O.Ol to 5 cent:imeters is suitable for most applications. Further, for some applications, the 10 web can be a layer in a composite multi-layer structure. For example, another lay can be a nonwoven web. The other layers can be attached to a layer of the inventiva melt-blown web by conventional techniques such as heat bonding. Suitable materials for such 15 layQrs include other high temperature stabla materials such as polyesters or polycarbonates. Webs, or composite structures including webs formed by this process can be further processed after collection or assembly such as by calendering or point embossing to 20 increase web strength, provide a patterned surface, and fuse fibsr~ at contact points in a web structure or the like; orientation to provide increased web strength;
needle punching; heat or molding operations; coating, such as with adhesives to provide a tape structure; or 25 the like.
Desired Web C_aracteristics for Microwave Cookinq The web of the present invention, which forms the pad for use in microwave cooking as described herein, must be grease absorbent (oleophilic) and 30 generally hydrophobic. Since the pad is placed in direct contact with food, it must be of neutral food grade material which will not leach any components into the food. In addition, it must not dehydrate the food by wicking moisture therefrom during storage together 35 in a sealed enclosure. The pad must further be formed of materials which can withstand the high temperatures necessary to properly cook the food by microwave ?) ~ r~ r~
~ 21 ~
radiation exposure~ It is al~o de~ira~Jle, of course, to make the pad as ~rease ab~orbent as possible to thereby reduce the si~e, thickness and weight of the pad, which i~ turn lowers the pad material requirements 5 and pad expense. In some appli,cations, it is desirable to bond the pad to another material, and thus ~orming the pad of a material with good bonding characteristics is neces~ary.
The blown microfibers (BMF) which comprise 10 the pad can be formed from multi-layer blends of polymer materials. In a preferred embodiment, the temperature stable polymer layer(s~ in each micro~iber consists of polyethylene terephthalate (PET), which has a relatively high melting temperature (above 4601,F) .
15 The other layer(s) of the microflber are preferably formed of polypropylene (PP). Polypropylene (PP) has excellent grease absorbent and hydrophobic characteristics for use in the multi-layer microfiber blend. Polypropylene alone a blown microfiber web 20 exhibits some melting for microwave applications in which fatty foods such as bacon are cooked. A multi-layer microfiber web of polypropylene (PP) and polyethylene terephthalate tPET) formed from the web formation process described herein has demonstrated 25 improved a~sorbency over previously attainable web structures (e.g., dry blended microfiber webs Of 50/50 polypropylene and poly 4-methylpentene-1) and exhibits no significant melting at those temperatures necessary ~or microwave food cooking.
30 This is believed to be the result of the "increased strength" o~ the coextruded web structure o~ the present invention over the extruded type prior web structure.
Polypropylene and polyethylene terephthalate 35 are such dissimilar polymers that it i5 difficult to form a usable melt-blown microfiber by dry blendlng the pol~ner pellets and extruding. Upon extrusion of a dry ;~ ~ r~ r~

blend o~ these po]ym~rs the polyethylene terephthalate forms excessive "shot" or "sand" in the polypropylene meltstream.
For -the high temperature or temperature 5 stable component, the material must have a hiyh crystalline melting point above 200C, such as polybutylene terephthalate (PBT), or polycyclohexane tsrephthalate (PCT) or a material with a high glass transition temperature above 60C (such as 10 polycarbonate (PC). In additic,n to the polyesters (PET, PBT, and PCT) mentioned above, other families of high temperature materials are also applicable.
Polyamides (nylon 6 or Nylon 66), polyolefins (such as poly 4-methylpentene-1 (PMP)) or polyphenylene sul~ide (PPS) may suffice. Of course, khis list is not inclusive--a person skilled in the art will racognize that other materials or properties will be fully applicable to this application.
Surface ~reatment of the web is necessary to 20 eliminate food sticking after cooking. One means to accomplish such surface treatment is to hot-xoll calender the web using a predetermined gap ~or a particular web thickness. Another means would be to flame treat the surface of the web. A ~urther means of 25 achieving a nonstick web cook surface is to attach a scrim on the food-side surface of the web. The scrim may also be calendered as it is attached to the absorbent coextruded web. The use of PET in the blended microfibers also provides a basis for heat 30 bonding a PET scrim to the web, if desired.
The multi-layer blown microfibers can be made with two layers, three layers or other numbers of layers within each fiberO The choice cf the number of layers is determined by the end use. When the 35 microfiber web is exposed to heat subssquent to the formation of the web, such as in embossing or calendering, the bonding component can ~Ifilm over" the ~7 ~ ~
- ~3 -high temperature component. In other words, the bonding component ~PP) can melt and coat the high temperature component ~PET) with a thin film o~
polypropylene. A two-layer m~crofiber construction (one layer PP and one layer PET) will result in a web where there is less chance ~or filming over o~ the PET
during calendering and more PET is exposed ~or lamination of a PET scrim to the web. A three-layer microfiber construction (one layer PET and two layers 10 PP) results in less exposed PET and thus more filming over of the polypropylene during calendering. This results in a less fuzzy surface ~or the calendered side of the web, which may be preferred for some applications.
The following examples are provided to illustrate presently contemplated preferred embodiments and the best mode for practicing the invention, but are not intended to be limiting thereof.

TEST PROCEDURES
Tensile St~e ~th Tensile strength data on a blown microfiber web having multi-layer B~F microfibers was obtained using an Instron Tensile Tester (Model 1122) with a 25 10.48 cm (2 in.) jaw gap and a crosshead speed of 25.4 cm/min. (10 in./min.). Web samples were 2.54 cm (in.) in width and samples are taken both in the machine direction (MD) and in the transverse direction (TD) of the web. Each sample was stretched until failure, with 30 the break force measured at failure.
Mineral Oil Absorption This test indicates the oil absorbency of a grease absorking pad. The pad, measuring 397 square centimeters (61.5 square inches), is weighed, soaked in 35 mineral oil at room temperature (about 20C) for 30 seconds, agitated in the oil, and left for another 30 seconds. The pad is then hung for 2 minutes to allow 2 ~ 7 - 2~ -excess oil to drip out of the pad and weiyhed to determine the amount, in grams, of mineral oil absorbed and held by the pad.
Maximum Grease Absorp~ion Under ~ookinq Condltions This test is used to determine the maximum amount oE grease that is absorbed by a pad by cooking 12 slices o~ bacon. A preweighed pad measuring 15.2 cm by 26 cm (6 inches by 10.25 inches) is placed in a microwave cooking package as described by FIG5. 1 3.
The bacon is placed on top of the pad and the bacon in the packaye is cooked in a 700 watt microwave oven for 7.5 minutes. The pad is then removed from the package and hung until dripping of grease substantially stops (about 30 to 45 seconds). The pad ls then 15 weighed (as compared to the pad 15 precooking weight) and the amount O:e grease absorbed i5 determined.
Example 1 A polypropylene/polyethylene terephthalate BMF web of the present invention was prepared using a 20 meltblowing process similar to that described, for example, in Wente/ Van A., "Superfine Thermoplastic ; Fibers," in Industrial En~ineerinq Chemistry, Vol. ~8, pages 1342 et seq (1956~, or in Report No. 4364 of the Naval Research Laboratories, published May 25, 1954, ~5 entitled "Manufacture of Superfine Organic Fibers" by Wente, Van A.; Boone, C.D.; and Fluharty, E.L., except that the BMF apparatus utilized two Pxtruders, each of which was equipped with a gear pump tv control the polymer melt flow, each pump feeding a three-layer 30 feedblock assembly similar to that described in U.S.
Pat. Nos. 3,480,502 (Chisholm et al.), 3,487,505 (Schrenk) or 4,197,069 (Cheren), which was connected to a melt-blowing die having circular smooth surfaced orifices (10/cm) with a 5:1 length to diameter ratio.
The first extruder delivered a melt stream of polypropylene (PP) resin (PP 3860X, available from Fina Oil & Chem. Co.), to a gear pump which feeds a three-'7 ~
- 25 w layer ~e~dblock assembly which was heated to about 3000c. The second extruder, which was maintained at about 3000C, delivered a melt stream of a polyethylene terephthalate resin (PET, having an intrinsic viscosity 5 of 0.60, and a melting poînt of about 257C prepared as described in U.S. Pat. No. 4,939,008, col. 2, line 6, to col. 3, line 20) for a second year pump which also feeds the feedback assembly. The polymer melt streams were merged in three layers on exiting the feedblock.
10 The gear pumps were adjusted so that a 50/50 weight percent PP/PET polymer melt waC; delivered to the feedblock assembly and a 0.11 kg/hr/cm die width (0.6 lb/hr/in.) polymer throughput rate was maintained at the BMF die. The primary air temperature was 15 maintained at approximately 3050c and at a pressure suitable to produce uniform web width with a 0.76 mm gap width. Webs were collected at a collector to BMF
die distance of 50.8 cm (20 in.). The resulting BMF
web, comprising three-layer microfibers having an 20 average fiber diameter less than 10 micrometers, had a thickness of about 0.150 in., and a basis weight of about 200 cJm/m2.
An electron micrograph preparation illustrating the laminar and uniform blending of the PP
25 and PET in the blown microfibers made by the process described above is shown in FIG. B herein. The electron micrograph of FIG. 8 was prepared in the same manner as described above with resp~ct to FIG. 7. The dark portion of each microfiber section shown in FIG. 8 30 is PET polyester, while the lighter portion represents the polypropylene.
The surface of the blown microfiber web is smoothed by calendering the web with one surfac of a calendering roll heated to a temperature of about 260F
(127C) while the other roll is kept at ambient or room temperature. These rolls are illustrated in FIG. 6 as calender roll 52 and heated calender roll 54. A gap of ~3 r ~ 26 -0.050 inch (1.27 mm) betweerl two lO lnch diameter (25.~ cm) ca]ender rolls 52 ~nd 54 produces an acceptabl~ surface on a web that is about 0.150 inch (3.8 mm) thick. The web is advanced through ~he 5 calender rolls 52 and 54 at a speed of 8 feet per minute t2.4 meters per minute~.
The web was then tested for mineral oil absorption, and cooking twelve slices of bacon. No visible melting was observed in the pad a~t~r the 10 cooking tests. The test results for oil absorption and tensile strength are summarized in Table 1.
Exam~le 2 A BMF web was formed accordin~ to the procedure of Example 1. During the calendering proces~, 15 a nonwoven polyester scrim (Reemay 2250 available from Reemay Corporation) was laminated to the BMF web. rrhe nonwoven scrim was positioned between the heated calender roll and the BMF web and the heated calender roll was heated to a temperature of 160C (320F) to 20 effect the lamination. No visible melting was observed in the pad after the cooking tests. The test results for oil absorption and tensile strength are shown in Table 1.
EXample ..3 A BMF web having a basis weight of 200 grams per square meter was prepared according to the procedure of Example 1 except that a two-layer ~eedblock was used. The resulting two-layer microfibers had an average fiber diameter of l~ss than 30 10 micrometers and the web thickness was about 3.8 mm.
(0.150 inch).
An electron micrograph preparation illustrating the laminar and uniform blending of the PP
and PET in the blown microfibers made by the process 35 described in this Example 3 (using a two-layer feedblock) is shown in FIG. 9 herein. The electron micrograph of FIG. 9 was prepared in the same manner as ~ 2l -describ~d above with respect to FIG. 7. The dark portion~ of each microfiber section shown in EIG. 9 is PET polyester, while the llghter port:ion represen-ts polypropylene.
No visible melting was observed on the web after the cooking ~ests. The calendered web was kested for oil absorbency and tensile strenyth, and test results are shown in Table 1.
Example 4 A BMF web was prepared according to the procedure of Example 3 except that the gear pumps were adjusted so that a 75/25 weight percent PP/PET polymer melt was delivered to the ~eedblock assembly. The resulting BMF web, comprising two-layer microfibers 15 having an average diameter of less than 10 micrometers, had a thickness o~ 3.8 mm. (0~ 150 inch) and a basis weight o~ about 200 grams per square meter. The web was tested for oil absorbency and tensile strength and the test results are shown in Table l. No visible 20 melting was observed on the pad after the cooking tests.
comparative Example C1 A BMF web was formed according to the procedure described in U.S. PatPnt No. 4,873,101 (incorporated herein by reference). The composition of the microfiber was 50/50 weight percent polypropylene and poly 4-methylpentene-1 (MX-007 TPX brand resin from Mitsui Petrochemicals America, LTD). The web had a basis weight of 200 grams per square meter and was 30 calendered according to th~ procedure described in Example 1. Test results for oil absorbency and tensile strength are shown in Table 1.

~7'7~
- 2~ -Ta~ble 1 ___~. =--__ =~= ___ Example Mineral Maximum Tensile Strength Oil Grease Newtons/Decimeter Absorbency Absorbency _~
gms/397 gms/397 MD TD
sq.cm. sq.cm.
I --- ~ __ _ I . _. _ ~-_ __ .
I _2 66 _77 __ 84__ 105 l _ ___ 4 108 _ 80 ~124 _ I C1 5~ _ 65 1621 Table 1 shows the superior oil absorbency and tensile lo strength of the inventive F3MF webs made with multi-layer microfibers.
Water Absorbency The microwave cooking pad should be hydrophobic in nature so that it does not absorb water 15 from the food and dehydrate the food during transportation and storage, and so that the capacity of the pad to absorb grease during cooking is not inhibited by the water produced during cooking of the food. ThP moisture or water absorbency of the pads 20 were tested by packing four slices of bacon teach weighing about 22.7 grams (0.8 ounces)~ in a sealed package with (1) the tared BMF pad of Example 1 measuring 15.2 cm. by 26.0 cm. (6 inches by 10.25 inches) and weighing about 9.6 grams, or (2) a tared 25 paper towel (Wyp All) weighing about 7.0 grams. The sealed packages were constructed by heat sealing together two sheets of 0.005 cm. (0.002 inch) thick "Scotchpak" brand film (sold by Minnesota Mining and Manufacturing Company) measuring 30.5 cm. (12 inches) 30 by 25.4 ~m. (10 inches). The sealed packages were held - 29 - 2 0 17 ~ 3 at 4C (40F) for ~our days. After four days the pads were removed and weiqhed to determine the amount of moisture pick absorption. The BMF pad weiyhed 11.4 yrams and had absorbed about e:ighteen per~ent by weiyht 5 water and grease whil~ khe Wyp All pad weighed 11.9 grams and had absorbed about 69~ by weight water and grease. The BMF pad was dried at 121C ~50F) for about one hour and the actual moisture absorption was determined to ba about nine percent.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recoynize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A pad for use in the cooking of food placed thereon in a microwave oven wherein the food contains a substantial amount of solidified grease which melts when the food is cooked by microwave radiation, the pad comprising:
an entangled web formed from at least one generally hydrophobic and grease absorbing multi-layer microfibers, said web being prepared by combining at least two streams of flowable materials in a layered, combined flowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruded flowstream with a high velocity gaseous stream to form a fiber and collecting the fiber on a collective surface so as to form the entangled web, with the pad being capable of holding the amount of grease in the food when the grease is melted by cooking the food in a microwave oven.

2. The pad of claim 1 wherein the separate streams of flowable materials comprise a stream of polypropylene and a stream of polyester.

3. The pad of claim 1 wherein the polyester is polyethylene terephthalate.

4. The pad of claim 1 wherein each microfiber comprises, in transverse cross section, a plurality of alternating laminate layers of the flowable materials.

5. The pad of claim 1 wherein the combined flowstream contains two separate flowable materials, with one of the materials constituting between 20 to 80 percent by weight of the combined flowstream.

6. The pad of claim 1 wherein the combined flowstream contains substantially equal parts by weight of two separate flowable materials.

7. The pad of claim 1 wherein the combined flowstream contains two separate flowable materials in a substantially 3:1 ratio by weight.

8. The pad of claim 1 wherein each microfiber is less than 20 microns in diameter.

9. The pad of claim 1 wherein each microfiber is less than 10 microns in diameter.

10. The pad of claim 1 wherein the pad includes first and second major opposing surfaces with said first major surface having been calendered to form a relatively smooth surface thereon, and with said first major surface adjacent said food.

11. The pad of claim 10, and further comprising:
a web formed from a high temperature stable material bonded to the second major surface of the pad during calendering of the pad.

12. The pad of claim 1 wherein the pad includes first and second major opposing surfaces, and further comprising:
a web formed from a high temperature stable material, the web having first and second major opposing surfaces, the first major surface of said web being bonded to the first major side of said pad, with the second major side of said web adjacent said food.

13. The pad of claim 12 wherein the high temperature stable material is polyester.

14. A pad for use in a microwave oven package, wherein the package includes a vapor-tight microwave radiation transparent enclosure that surrounds both the pad and food to be cooked by microwave energy, with the food containing a substantial amount of water and solidified grease, the pad comprising:
an entangled web formed from at least one generally hydrophobic and grease absorbing multi-layer microfiber, said web being prepared by combining at least two streams of flowable materials in a layered, combined flowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruded flowstream with a high velocity gaseous stream to form a fiber and collecting the fiber on a collective surface so as to form the entangled web, with the pad being capable of holding the amount of grease in the food when the grease is melted by cooking the food.

15. A package for use in a microwave oven, said package comprising:
(a) food to be cooked by microwave energy containing a substantial amount of water and solidified grease;
(b) a pad adjacent said food comprising an entangled web formed from at least one generally hydrophobic and grease absorbing multi-layer microfiber, said web being prepared by combining at least two streams of flowable materials in a layered, combined flowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruded flowstream with a high velocity gaseous stream to form a fiber and collecting the fiber on a collective surface so as to form the entangled web, said pad being capable of holding the amount of grease in said food when said grease is melted by cooking said food;
and (c) a vapor-tight microwave radiation transparent enclosure surrounding said pad and said food.

16. In a microwave oven package which has a vapor-tight microwave radiation transparent enclosure that surrounds food to be cooked by microwave energy containing a substantial amount of water and solidified grease and that surrounds a pad adjacent to the food, the improvement which comprises:
forming the pad from an entangled web formed from at least one generally hydrophobic and grease absorbing multi layer microfiber, said web being prepared by combining at least two streams of flowable materials in a layered, combined flowstream, extruding the combined flowstream through a die having at least one orifice, attenuating the extruded flowstream with a high velocity gaseous stream to form a fiber and collecting the fiber on a collective surface so as to form the entangled web, with the pad briny capable of holding the amount of grease in the food when the grease is malted by cooking the food.