CA 022492~8 1998-09-1~
FLEXIBLE LIGHTWEIGHT PROTECTIVE PAD
FIELD OF THE INVENTION
The present invention relates to protective padding for the human body. The present invention has further relation to such protective padding that is lightweight, impact-absolb~lt, 10 flexible, and breathable.
BACKGROUND OF THE INVENTION
Hip pads, and other protective pacltling have been used for pl~)t~hlg the human body from damage due to impact from falls, accid ~1~, sports, and other related events. In particular, ~5 bone fracture as a result of ~ ccid~ ~-t~l falling is a common OCCul~- nce with elderly people, with people who have a o~leoporosis, and people who are u,. ,teady on their feet and have difficulty in walking. In elderly people, especi~lly those with Ost..opf..usis, bone rl ~ ~,s are very difficult to repair, and it is highly desirable to prevent them from oc~ullillg in the first place.
A variety of protective padding and ga.llle.lb have been made available in the past, but 20 all with some shortcomingc A typical piece of protective wear is a pad that is either permanently fixed to a garment, or that slips into a pocket in the garment, or held in place by straps or a skin-safe adhesive so that the pad is po~ilioned over a damage-prone area of the body.
Such a damage-prone area, especi~lly in the elderly, is the hip area. Hip fracture, which occurs in 2 to 3% of cases involving elderly fallers, generally involves fracture of the proximal end of the 25 femur. This part of the femur consists of a head, neck, greater lrochallt~ ~, and lesser llucL...Ite..
The greater lruch~t~ . projects outward at the most lateral area of the hip region and, being so located, is ~ubje,t d to the brunt of impact force arising from a fall, in particular a sideways fall, onto the hip.
To protect the hip area, pads are typically fixed to the inside of clothing in the area that 30 covers the hips, or are placed in pockets made in the clothing at the hip area. More specifically, the pads are typically posifionPd such that they overlie the greater llu-h :, or, in the case of certain types of force or energy shnntin~ pads, ~u"ou..d the greater lluch~ without actually covering it.
The degree to which a pad needs to hlt~ ul~e the force of impact during a fall is subject 35 to much debate. This is because c.eaiu,.i.,.~ t~ of the force needed to fracture elderly cadaveric femurs in simulated fall loading configl- ations vary widely. These ."eas,l,l.l,e.,l~ range from CA 022492~8 1998-09-1~
2110 Newtons (J.C. Lotz & W.C. Hayes. J. Bone Joint Surg. [Am]~ Vol. ~. pp 689-700, 1990) to 6020 Newtons (T.G. Weber, K.H. Yang, R. Woo, R.H. Fitzgerald. ASME Adv. Bioeng. BED22:
pp 111-114, 1992) depending upon the rate of loading. In a-lrlition~ the velocity at which a falling human torso impacts a hard surface such as a tile floor can vary from about 2.0 to about 5 4.5 meters/second. Average velocities of about 2.6 meters/second have been cited by resea~,he.~
(S.N. Robinovitch, 1. Biomech. Eng. Vol. 9, pp 1391-1396, 1994) who have measured the speed of human volunteers falling on their hips. FctimAt~s of the force delivered to an un~ ded greater trochanter during a fall also range widely from about 5700 Newtons to 10,400 Newtons (J. Parkkari et al., 1. Bone and Mineral Res., Vol. 10, No. 10, pp 1437-1442, 1995).
I0 The best evidence of pad effectiveness is obtained from clinical studies on living people.
Such a study has been carried out by ~auritzen et al. (Lancet, Vol. 341, pp I ~-13, 1993) using a hard shell-type pad. This pad was found to reduce incidence of hip fractures by about 50% in the population studied. In spite of these strong clinical results, the Laurit~en pad has been shown to provide relatively low force All'~ l io~ results when mounted on a surrogate hip and ;---p~ t.~ d 15 by a heavy (35 kilogram) per ~ lnm moving at a velocity of 2.6 meters/second (S.N.
Robinovitch, et al., 1. Biomechnical Fng;..e~.hlg~ Vol. 117, pp 409-413, 1995). Under these in-vitro test contlitionc~ the Lauritzen pad reduced peak femoral force from about 5770 Newtons to about 4800 Newtons or only about 17%. A hip plut. .,lor product based on the Lauritzen pad has been con.,.,~ ialized in Denmark by Sahvatex (a joint venture between Sahva A/S and Tytex 20 A/S) under the tradename SAFEH~PTM. The hip p~uIe~;lu.a~ which are oval-shaped cups contAinin~ polypropylene hard shells, are sewn into a pair of cotton underwear.
These clinical findings suggest two hy~.ulh~ses First is that the pendulum impact tests used by other investig , may not collel~t~, well with pad performance in-vivo even though such tests may be useful in ...e&~u. ing the force redu~tion capabilities of various padding systems 25 relative to one another. In such tests the pad is mounted on a surrogate hip which is held in a fixed position and struck laterally by a swinging mass weighing 35 kilograms or more. In an actual fall, the dynamics are SOIl.~,~ Ld~ different. In a fall, both the pad and hurnan body mass are moving downward, in fact being accel~ t~,d downward due to gravity, and strike a fixed object such as the ground or a hard floor which does not move much in ~ onse. One would 30 suspect that if an inst~m~ontpd aullu~ale hip was dropped onto a hard surface, to better replicate fall dynamics, the rank o~e.-ilg of various padding systems would probably be simi1ar, but somewhat di~fe.-l percent force red~ction results might be obtained. The second hypothesis assumes the pendulum test does cull~ila~e with in-vivo pad performance, and that even pads which provide relatively low levels of peak force reduction (about 20% or so) can be effective in 35 reducing hip LacIu.es across a S~E~ ~11 of the elderly population prone to falling. In either case, CA 022492~8 1998-09-1~
and regardless of test method, a pad which reduces peak force more than the clinically tested Lauritzen/Sahvatex pad should be even more effective in preventing hip fracture and protect an even broader segment of the elderly population.
Obviously, the more force reduction one obtains from a pad, the more likely it should S reduce the incidence of hip fracture. However, our consumer r~,sedr~h has taught us that, in addition to reducing the impact force exerted on the greater ~ chh~ . during a fall. pads must also provide other benefits to reinforce wearer compliance. These are related to both appea,..nce and wearer comfort and include attributes such as maximum thickness, thir~nPcc profile, weight, breathability, flexibility, and confol,llability to the body, Prior pads have had many 10 shortcQrnin~c in these areas.
Some prior art padding has been bulky and cumbersome in an attempt to provide for ~dequ~te protection from impact; many typical prior art pads purported to provide effective impact resict~nce are greater than 25 4 mm (I inch) in thir~nPcc Thin prior art pads typically provide low re -~e from impact, chalact~ ,d by less than 30% peak force reJueIion as 15 Illeasul~d on surrogate hips either dropped or struck with heavy pen~uhlmc Other padding has not been breathable, resulting in heat buildup on the skin that is covered by the pad. Still other padding has been stiff and rigid, thereby not confoll..ing to the covered body parts. In ~ddition~
hard shell pads tend to be uncomfortable to sit on or sleep on when worn. Soft foatn pads require greater thickness to absorb impact forces; the greater thirl~nPcc results in a bulkier, less 20 comfortable pad, and hlcl~;ed heat build up under the pad. All have resulted in relative discomfort to the users.
Our CQnC~ ~ res- cll has shown that potential wearers, regardless of age or physical condition, are conce.llcd with their appealance. Plef~,"~,d are hip pads no thicker than about 25.4 mm (one inch), and more p-~f~ ,d are those about 19 mm (3/4 inch) maximum thir~n~Pcc or less 25 Thir~nPcc profile is also hllpOIla~lI Plcl~ d are pads which are tapered from the area of m~Yim~. n thic~nPcc to the p~ -ete. such that the pad edges do not show under normal c!r~thin~
A pe.;--l-,t.r thir~nPcc range around the pad of l2~77 mm (I/2 inch) or less is generally p~f...ed.
Even more p..,f;~l-cd is a pe.;---~t,r thic~nPcs range of 6~35 mm (1/4 inch) or less.
Since most p: nti~i wearers are elderly women of slender body habitus and low body mass, pad weight is a concern~ ~ef,.-~,d are pads less than about 300 grams each (600 grams per pair)~ Even more p.ef .-cd are pads which weigh less than about 200 grams each (400 grams per pair)~ Most p-efe.-cd are pads which weigh less than about 100 gratns each (200 grams per pair) Unlike sports pads which are meant to be wom over very shott periods of time, p~t~ ive hip pads for the elderly are in~l dcd to be worn all day, indoors and outdoors, in all climates hot and cold, and across all humidity condhionc Typical foam pads are made from closed cell foams which do not pass moisture or pe,~yi~alion from the body. In addition, such pads are thermal insulators and do not discir~te body heat effectively. This ieads to even more pe,~.halion and moisture buildup under the pad which can damage the skin of elderly wearers.
Preferred pads thus have subst.9-nti91 open area, preferably at least about 5% or more, and more S preferably about 10% or more, to permit evaporation of pe.s~ tion and to vent body heat.
Disclosed herein is a new, improved protective pad<ling that provides hl~-~,ased impact resict-qnce in a relatively thin, lightweight pad. Increased impact resistance is m~int-sin~d while providing breathability to prevent heat buildup and the associated discomfort. Additionally, this new pad provides for flexibility and conformance to the part of the human body being p,~,ti~,t~,d without any adverse impact on its plotGclive qll~litiPs.
SUMMARY OF THE rNVENTlON
In acco,dance with the present invention there is provided a protective pad for plo~ ;li"g a predefined area of a human body against impact, the pad having a surface and a thir~npcc~ the pad comprising a layer of high density closed-cell polymer foam on the outer surface of the pad away from the wearer's body, and a layer of low density closed-cell polymer foam on the inner surface of the pad against the wearer's body. Typically, the high density foam has a density of from about 128 to about 192 kg per cubic meter (about 8 to about 12 pounds per cubic foot) and plefe.~.bly about 160 kg per cubic meter (about l0 pounds per cubic foot). The low density foam typically has a density of from about 48 to about 80 kg per cubic meter (about 3 to about 5 pounds per cubic foot) and prcfe.ably about 64 kg per cubic meter (about 4 pounds per cubic foot). The layers are fixed together to provide a relatively lightweight pad providing relatively high nes;~ ce to impact forces and relative comfort to the user.
The pad may have a plurality of score lines across the outer surface and partially through the thir~r~Qc so as to provide sul s~ isl flexibility and conf~"",ability to the area of the human body covered by the pad, without significantly ar~;~,ting r~ nre to impact forces. The pad may also have a plurality of open areas on the surface and co...ph:1 ly through the thic~nPcc so as to provide for breathability and clicci~ ;on of heat from the area of the human body covered by the pad, while ~sjntsinjng significant ~ e to impact forces.
~ ln general, the pad weighs less than about 75 grams and has a mqximllnn prGrL.lGd th jc~n~cc of less than about 25.4 mm. The overall size of the pad or area covered by the pad may range from about 96.7 to about 322.6 square cm (about lS to about 50 square inches). The pe.~ tage of open area can range from about 10% to about 50% depen~ling upon the overall size of the pad. In general, the pad's pe~ e of open area is selected so as to provide m~iml-m 35 ventilq-tion while still providing 40% or more peak force r~.du~:tion as ea~uid in a ~ul~og.h hip -impact test.
Such pads can be either permanently or removably attached to a garment The garments are preferably made of fabric which promotes wicking of p~,.a~ lion buildup away from the human body.
BRIEF DESCRIPTION OF THE DRAWrNGS
While the specification concludes with claims particularly pointing out and distinctly clqimine the subject invention, it is believed the same will be better understood from the following description taken in conjunction with the q-ccQmp~rlying drawings in which:
Figure I is a plan view of a p~ut~ e pad of the present invention.
Figure 2 is a partial cross-sectional view through lines 2-2 of Figure I .
Figure 3 is a plan view of an alternative embodiment of a protective pad of the present invention.
Figure 4 is a pe.~,e~ e view of the hip pad of Figure I showing the pad in a flexed 15 position.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings in detail wherein like numerais indicate the same element throughout the views, there is shown in Figure I an embodiment of the present invention, 20 p~ ecli~e pad l0. The ~,lùt~ e pad 10 is relatively lightweight, and is relatively thin (less than 25 mm in thi~ n~cs, but most preferably 19 mm or less). It also may be relatively flexible and cont~ d as .e~uhed d~pending on specific use, as will be des_l;l,cd in more detail h_.eaf~er.
The pad 10 has a high degree of open area through its thickness for breathability while ~qintqinine significant impact recictqn~ as shown by holes 12. The present pad 10 also 25 el~.,~ ,ly reduces the force of an impact app~v~i...~tely 40 to 50 % ûver the impact force e,~ e.,ced without p,~ ti~
The pad l0 may h made in a variety of shapes based on the particular desired style and application, such as re.~ g,llq~ {as shown in Figure 3), square, round, oval and the like. Holes 12, for breathability and d ~ on of body heat under the pad, can range from about 3.18 mm to 30 about 25.4 mm in diameter d~pc~ ng on the levels of bl~ bility and impact resistance desired. Other shaped holes such as ovals, squares, and the like can also be employed. The surface area de~ ' to holes 12 must be great enough to provide for s~ nt ventilqtion but not so great as to lower the peak force reduction capability of pad 10 to less than about 40%; the area dc~ic-l~'d to holes 12 may range from 10 to 50 percent of the total surface area while 35 mqintqining significant impact rc~ nre. Pad 10 may be retic~ by slicing partially through CA 022492~8 1998-09-1~
W O 97~3493 PCTAus97/03042 its thickness, producing scorelines 14. Scorelines 14 are cut preferably from a depth of about 1/4 to 3/~ of the overall pad thickness, and across the surface area~ as shown in Figures I and 3.
Scorelines 14 are cut or molded into the pad from the outer surface or high density foam side of the pad. This makes the pad very flexible and able to conform to a wide Mnge of shapes and 5 sizes. The flexibility imparted by scorelines 14is shown in Figure 4.
The pattern and spacing in which the scorelines are applied can be varied. For illustrative purposes, Figures 1, 3, and 4 show the scorelines cut at + or - 45 degrees to the straight edges of the pads and running through the centers of the holes in the pads. The scorelines can also be cut at 90 degrees to the straight edges of the pad or any angle bet~veen + and - 45 degrees and 90 10 degrees to the edges. The scorelines can run through the holes, between the holes, or in combinations through and between the holes. The scorelines need not be cut as straight lines parallel and perpendicular to one another as shown in Figures 1, 3, and 4. They can also be cut in a fan shaped array from one side of the pad. They can be curved, sinusoidal, or zigzagged across the pad. P~efe.l~d spacing between the scoleli"es lies between about 6.53 mm and about 50.8 15 mm. Even more ptefe~d spacing between the scorelines lies between about 12.77 mm and about 25.4 mm.
The pad is made with two different types of foam materials. The outer impact layer 16 is a stiff high density material, ple~lably a closed-celled polymer foam, for example Voltek L1000 polyethylene foam (Voltek, La~ nce, Mf -' ~5 01843). The inner layer 18 is a soft low density cushion material, also preferably a closed-cell polymer foam, for example Sentinel MC3800 polyethylene foam (Sentinel P~udu~,la Co,~,ola on Hyannis, ~1~c~cl---$ettc 02601).
The outer layer 16is able to provide m~Yim~l impact absoll,~.nce and is stiffenough to prevent the pad from bottoming out when under impact, while the inner layer 18 provides comfort and the degree of flexibility needed to confo.,.l to various parts of the human body; the end result is a combination of n~ m effectiveness and comfort. The pad 10 can be made by l~min~ting the two layers together and then shaping it by mech~nir~lly ~il,d;ng it, using shaping rolls and a skiving blade. Alternatively, the pad can be made by heating the t~,vo layers and compressing them together under heat and ple~a~llc. Such - ~ ing methods are known to those skilled in the art.
The pad materials are closed cell foams, preferably polyolefin closed cell foams, but other materials with similar plo~ ies can also be employed. Suitable polyolefin closed cell foams are derived from low density polyethylenes (LDPE), linear low density polyethylenes (LLDPE), medium density polyethylenes (MDPE), high density polyethylenes (HDPE),ethylene-vinyl acetate copolymers (EVA), ethylene methyl acrylate copolymers (EMA), ethylene 35 ionol,.~a, polypropylene and polypropylene copolymers. These polyolefin materials are CA 022492~8 1998-09-1~
preferred because they do not absorb water or pe.~ i.alion, nor support microbial growth, and are generally non-irritating and non-senciti~ing to the human skin. Suitable other materials can include rubber foams derived from natural rubber, butyl rubber, polyisop~eac, polybnts-~iPn~
polynu, l o, ncne, styrene-butadiene, neo~"~..c, nitrile rubber, and related rubber materials, polyurethane foams, and plasticized polyvinylchloride (PVC) foams. Although the other materials, like the polyurethanes or rubber foams, can perform at desirable impact ft~ C
levels, care must be taken in selecting such materials for pads to be used in direct or indirect contact with human skin. Special grades of each, known to those skilled in the art, can be formulated to inhibit the absorption of water or p~ ,i.alion~ to prevent microbial growth, and to 10 prevent skin irritation and se~ ;on, all of which lead to user discomfort or are de~ c.l~al to the user's health The outer layer 16 has a density of from about 128 to about 192 kg per cubic meter (about 8 to about 12 pounds per cubic foot) with about 160 kg per cubic meter (about 10 pounds per cubic foot) being the p.ef~.,cd density, and the inner layer 18 has a density of from about 48 I5 to about 80 kg per cubic meter (about 3 to about 5 pounds per cubic foot) with about 64 kg per cubic meter (about 4 pounds per cubic foot) being the p.ef~..cd density When each layer is made at the high end of its density range, msYim.~m impact resict-snre results. When each layer is made at the low end of its density range"..~ . comfort results. The preferred values result in a combination of Ci~ificsrlt comfort and impact ~c,;~l ~ce in one pad. Aflditions~ly, providing a top or outer high-density layer with a thir~ s of at least 50 percent of the overall pad thir~nesc msYimi~ps pe.ru. ~ --e ofthe pad.
Comfort in wearing hip pads can be er~h~ ed by g~lllc.lt design. The garment fabric can enhance breathability, particularly when combined with a pad with air flow openingc Fabrics which P~ OI~ wicking of natural moisture away from the skin promote te,.-p~ ~.e regl~lstion and comfort. "Cottonwick", .n~ .r; ~m-~,d by Colville Inc. of Winston Salem, Nor~h Carolina, is a particularly eff~ re fabric for this purpose. It has a uni4ue knit loop with poly--.c-;L~.d silicone coating that wicks I~O;~,tU~c into the fabric. The knit loop forms cone shaped capillaries and the silicone coating directs the moisture away from the surface of the fabric into the cones.
The pads of the current invention may be pennanently affixed to the garment by, for example, sewing them into pockets such that the pads cannot be removed. Pads used in such a ga-.~ hclefu.e need to be at least hand v,~ ' -ble with the gar nent, and p.ef,.ably m ~hin~o washable. After washing, the garrnent and pads must be dried. Both line drying in room temperature air and m~rhine drying with heated air are facilitated by tbe open areas in the pads which promote airflow through both the garment fabric and the pads. Alternatively, the garment CA 022492~8 1998-09-1~
may have poc~ets which are made openable and reclosable by means of zippers, snaps, hook and pile fasteners, and the like. This allows the pads to be removed from the garment such that the garment can be washed separately if desired.
The following examples are illustrative of the invention but are not limiting thereof.
s Example 1. MPc~ ined Foam Laminate Pad A multilayer pad is constructed by first die cutting a piece of MC3800 polyethylene foam (Sentinel Products Corporation, Hyannis, I~ cl.~cell~, 02601) having a density of 64 kg per cubic meter from 9.52 mm thick sheet such that the piece has two straight sides ol~posile one 10 another and parallel to one another and two curved sides opl)o5ile one another as shown in Figure 1. Twelve 12.77 mm diameter holes spaced around the piece are die cut at the same time. The distance between the straight sides is about 127 mm and the distance between the curved sides measured through the center of the piece is about 139.7 mm. This first piece is the skin or wearer side of the pad.
A second piece of foam, circular in shape and about 114.3 mm in diarneter, is die cut from 9.52 mm thick Minicell L1000 polyethylene foam (Voltek, La~ nce, ~vlA~rkl c~tl~ 01843) having a density of about 160 pounds per cubic meter. This piece also has twelve 12.77 mm di~ h, holes die cut at the same time and having the same spatial a~ .t as in the first foam piece.
20 This second piece is the outside of the pad away from the wearer's body.
The two foam pieces are l~in~d together with 3M #343 double sided adhesive tape (3M Co., St. Paul, ~ n~sot;~ 55144) such that the twelve holes in each piece are aligned with one another.
The laminated ass_...bly is then mech~nil~slly m~cllined using a cup shaped grinding wheel to 25 provide smoothly t~,~.i..g sides to the pad in all directions and to give the l~minst~ a domed or curved cross section with the L1000 foam residing on the outermost or convex side of the pad.
This is shown schematically in Figure 2. The finished pad weighs about 15 grams and has an open area of about 12%. The msYiml-m ll.i- L~.~c$ is about 19 mm in the central areas of the pad lap~,.l.lg to about 6.35 mm or less around its pe. i--.~.h-.
The pad's ability to cushion against impact against a hard surface is n.e~...ed on a su..u~ t~, hip, constructed from polyolefin and neop.~..e closed cell foams as well as other c,~ po-~P-.I~i, and dc sig,.cd to mimic both the soft tissue r i"x)nse and pelvic response of a human hip in a fall. The s~lllugàle hip is dropped from a distance of about 37.5 cm such that its velocity upon impact with 35 a ho.izur.~i steel plate is about 2.7 meters per second. The a~llu~ale hip weighs ap~,.o~ 'y 35 kilograms-and contains a surrogate femur and surrogate greater trochanter. A 5000 pound load cell (Product No. 8496-01, GRC Instruments, Santa Barbara, California) measures the force transmitted to the surrogate greater t-o~l1a,~ when the surrogate hip is dropped on the steel plate. The force measured on the surrogate s trochanter when the unps.~l~ed surrogate hip is dropped and impacts the steel plate is about 6000 Newtons.
For cG.npalison with the pads of this invention, a hip plute~,lor is removed from a SAFEHIPT~
10 product (Sahvatex, Denmark), and mounted on the SullOgal~ hip and held in place over the area of the surrogate greater t,ocl.~nt~ . by means of a stretch fabric covering the outer skin of the hip.
When the padded su.lu~ale hip is dropped and impacts the steel plate at 2.7 meters/second, the peak force measured on the sullugdte t,ocha"t~. is about 30% less than that measured with the unrar~ded su,luga~e hip.
The pad of this Example is mounted on the sullu~dte hip and held in place over the area of the ~ullugdte greater lru-. h~ , by means of a stretch fabric covering the outer skin of the hip. When the padded Swlugd~: hip is dropped and impacts the steel plate at 2.7 meters per second, the peah~ force ll..,~u-cd on the sullug~e t~uchallt~,. is about 44% less than that uleasured with the 20 unratlded surrogate hip.
F ~mple 2. M: ~hined Foam Laminate Pad with Scorelines A pad identir~l to that described in Example I is con:,l.u.,ted. This pad is then scored from the L1000 side of the pad using an Exacto knife. The score lines are applied at angles + and - 45 25 degrees to the straight sides of the pads and are cut about 3/4 of the way through the total pad L~- 5S. The resulting pad is very flexible and artiCulst~ in multirle di,~,lions. When evaluated on the Sul-u~;~t~ hip drop tester, the peak force l.,casu.~d on the ~ull~gale trochanter is about 43% less than that ~ue&su-ed on the u.,~ Pd ~ullug~ate hip. Thus the score lines have virtually no effect on the force reducing ability of the pad.
Example 3. Compression Molded Pad A 152.4 mm by 152.4 mm piece of MC3800 foam 9.52 mm thick is cut from a larger sheet. A
second foam piece circular in shape and having a diz.llet~,. of 101.6 mm and a thirLn~ss of 15. 8 mm is cut from a sheet of L1000 foarn. The L1000 is l inqt~d to the MC3800 with 3M#343 35 adhesive tape such that the centers of the two pieces are aligned.
CA 02249258 lsss-os-15 The l~m jn~te is piaced in a convection oven and heated at 350 degrees F for 3 minutes. The laminate is then removed from the oven and immediately placed between the platens of an aluminum compression mold. When closed, the mold creates a crescent shaped cavity desigr~Pd S to provide a maximum thicknPss in the central area of the pad of about 19 mm, a smooth transition between the two foams, and a tapered cross section. The l~mjnqt~P is co".p,e~sed for 30 seconds at a p,~saure of 1900 pounds per square inch. Upon removing the l~minqte from the mold, a rule die is used to die cut the pad to its final shape as well as create twelve 12.77 mm diameter holes in the same spatial arrngPm~ntc as in Examples I and 2 and shown in Figure 1.
10 The resulting pad weighs about 21 grams. When tested on the surrogate hip drop tester at an impact velocity of 2.7 meters per second, the peak force ",easured on the surrogate l,~cl,a.,hr is about 40% less than that measured on the 1, ~- I'od surrogate hip.
To determine if the pad is stable to m~-' ~~ washing and drying, several pads were placed in a 15 ?~orge Heavy Duty washing m~~hine and put through 3 normal wash cycles using Liquid Tide d~,t~,.g~,..l. The water t~.Up~ UI~ was set on hot which is about 120 degrees Fah--,nheit on this m~~hinP Following the 3 wash cycles, the pads were placed in a Sears ICenmore Dryer and dried for 2 hours at about 180 degrees Fal,.. '-:1, much longer than the actual time needed to dry them. After washing and drying as desc- ;I,ed, the pads showed no visible signs of d_t, .;o-..;ion.
Exarnple 4. Colllp~ aion Molded Pad with ScGr~lines A pad jrlRntirql to that described in Example 3 is cOIlallu~;t~,d. This pad is then scored from the L1000 side of the pad using an Exacto knife. The score lines are placed in the same pattern as de,ic,;bed in Exarnple 2 and are also cut about 3/4 of the way through the pad. When evaluated on the au.lo~Sat~, hip drop tester, the peak force ~"easu-~d on the au~ te tlo~l ~t,~'. iS about 43% less than that ,lle~u.ed on the ~ p~ d swTogate hip.
Example 5. 12~Ct~g--lqr C~ .p.~,;,ion Molded Pad A piece of MC3800 foam, nolninqlly 127.0 wide and 177.8 mm long and 9.52 mm thick and having fifteen 25.4 mm ~ -et~ . holes as shown in Figure 3 is die cut from a larger sheet. A
second piece of foam, also 127.0 mm by 177.8 mm and also having fifteen 25.4 mm di~
holes is cut from a 15.8 mm thick sheet of L1000 foam. The two foam pieces are Iqminqt~d log~ . with the fifteen holes aligned using 3M #343 adhesive tape.
... . ..
CA 022492~8 1998-09-1~
The laminate is placed in a convection oven and heated at 350 degrees F for 3 minutes The laminate is then removed from the oven and immediately placed between the platens of an aluminum co~ lession mold with the L1000 side facing the upper or concave platen and the MC3800 side facing the lower or convex platen. When closed, the mold creates a crescent-5 shaped cavity designPd to provide a m~ximll-n thicknçsc in the central area of the pad of about 19 mm, and edges tapered to 6 3S mm or less around the pad p~,. hllct.,l The i~-nin~t~
is cu...~,.essed for about 30 seconds at a pressure of about 1900 pounds per square inch. The completed pad weighs about 41 grams and has about 33 % open area.
When evaluated on the surrogate hip drop tester, at a velocity of about 2.7 meters per second, the peak force on the surrogate IIU~ r is about 46% less than that measured on the n~.p7cld~d surrogate hip Example 6. RRct~ngul~ Pad with High Open Area and Scorelines A pad identir~l to that desc-;bed in F~rnple 5 is con~l.u~ted. This pad is then scored from the L1000 side of the pad using an Exacto knife. The score lines are placed in the same pattern as shown in Figure 3 and are also cut about 3/4 of the way through the pad. When evaluated on the ~u~ g -~ hip drop tester, the peak force u,e~wu-~d on the su~-~,gale l~ochant~,r is about 45 % less 20 than that ~-,ea~u.~d on the .- .pP1ded ~UIIU~;dt~ hip. Again, the p.ese..ce of the sco~el,..es does not sigllifi~ ~ tly impact the force reducing ability of the pad.
While particular embod;...~ n~ of the present invention have been illustrated and des_, ;bed herein it will be obvious to those skilled in the art that various changes and mo lifi~tiorlc can be made without departing from the spirit and scope of the present i"~r~,.,tioll 25 and it is ;-~ d to cover in the ~ppenr~ed claims all such ...odil,c_tions that are within the scope of this i,..c.r,lio--.