CA2131713C - Packing material - Google Patents

Abstract

2131713 9318911 PCTABS00025 A filling material (10) for use in filling hollow spaces in packaging or the like comprising one or more pieces of flexible paper material (12). The paper material has a plurality of individual slits (14, 16) formed in parallel spaced rows extending transversely from one end of the paper material to the opposing end of the paper material. The slits in adjacent alternate rows are positioned adjacent the interval space (20) between adjacent slits in the adjacent parallel row of slits. The flexible paper material (12) is expandable by extending the opposing ends (22, 24) of the paper material which are parallel to the rows of slits whereby the slits form an array of openings, each opening being generally hexagonal in shape and of the same size. The length and width of the flexible filling paper material can be varied. The construction of the flexible paper filling material provides it to be easily stored in the non-expandable position and easily expanded for use in filling hollow spaces in packaging.

Description

WO 93~1&911 P~/US93/02369 PACKING MATERlAL
BACKGROUND OF THE INVE~TION
Field Of The Invention The present invention relates in general to dunnage or cushioning materials for use as packaging or packing material and more particularly to a new and irnproved dunnage material for filling hollow spaces in packaging shipping containers and for wrapping articles.
Description Of The Prior Art Materials for use in filling hollow spaces in packaging or ~vrapping objects for protection in moving are well known in the prior art. However, to daLe, such materials have been either in-effective, such as newsprint, or ecologically unsound, such as styrofoam or plastic bubbles.
Production of the styrofoam and plastic bubbles causes toxic waste as well as creates disposal problems. Although recycling of these products is possible, storage of the products for reuse is bullcy and not generally feasible for home owners or some indLlstries. Another disadvantage of e~nsting filling materials is that they cannot be shipped in an unexpanded forrn thereby creating shipping cost based on buLk.
While the prior art devices provide improvements in the areas intended, none of the prior art overco nes the problems associated with general sJ~upping. None of the prior art patents dis-close an em~iromnentally safe material w~uch can be wrapped around, and conform to, a delicate item.
The instant inwntion disc!oses a enYirorlrnentally safe filling material manufactured from recycled paper in Yanous sizes to meet the user's needs. The cushioning affect of the fill-ing paper is achieved throu~ expallsio~n at the ~irne of use and therefore is shipped in an unex-panded form to provide an adv~tage for shipping and storage.
SUMMARY OF T~E INVENTION
The present invontion pro~ides a new and improved packaging material for use in wrap-ping objects and/or in filling hollow spaces in packaging or the like.
The expanded cushioning material is in the form of at least one sheet of an essentially flexible llon-wov~n fibrous material, preferably formed of biodegradable cellulosic fibers. The use of 30 pound paper is preferred. Most preferahly at least about 70 pound, recycled paper is used. Recycled paper having a stiffness greater than that of unrecycled paper and an average fiber length which is substantially less than that of unrecycled paper is preferred. The recycled paper has a substantially lower grain orientation tharl that of unrecycled paper, and conse- ', quently, a lower orientation memory and less of 8 tendency to return to the unexpanded cc~n-~guration than that of unrecycled paper. The paper material preferably has a thickness less than about 0.03 ~ches and the thickness c~ be on the order of about 0.02 inches.'.

SlJBS~lTUT~ S~IE~T

WO 93/18911 PCI/US93tO2~9 ,' ~.I,t ~ 3 2 Each sheet has, in its unexpand~d form, a plurality of spaced parallel rows of individual slits which are essentially straight lines on the order of about one-half inch long, extending trans-versely from one end of the paper material to the opposing end of the paper material. E:'ach of the rows is provided with interval spaces between consecutive slits, with the slits in adjacent rows positioned adjacent the interval space, placing the slits of one row essentially opposite the spaces of the next row. Preferably, the slits are arranged in a consistent, uniformly repeating pattern.
The flexible sheet paper material can either be expanded prior to the wrapping of the ob-ect with the paper or during the wrapping process.
The sheets are expanded by extending the opposing ends of each sheet which are parallel to the rows of slits forming an array of operlings. Each of the openings are generally similar in shape and size arld preferably are generally hexagonal in shape. The preferred pattern of slits produces polygons having an even number of side, and most preferably, produces a hexagon.
The filling material has an expanded thickness on the order of at least about ten times the unex-panded thickness of the sheet and preferably can be extended the order of t venty times the unex-parlded thickness of the sheet. The opening action causes the land, or solid, sections between slits to bend in a directio~ Dormal to the plane of the paper, providing the paper with an extreme in- -crease in effective thickness. The expanded sheet is formed of openings and land areas with at least a majority of the la~d areas Iying in a plurality of parallel planes, forn~ing an angle be-t~vee~ about 45 arld less than 90 degrees (at full expansion~ vith the plane of the sheets, and preferably orl the order of about 70 degrees.
The expanded cushior~ing material has a minimurn load bearing capacity of at least about 150 Ib. per square foot of expanded material. Preferably, the load bearing capacity is at least about 250 lb. per sq. foot. ~At a load beari~g capacity of at least about 400 Ib. per sq. foot, greater ur iversality of application is achieved and optimum cushior~ing cal~ be achieved in typi-cal applications with the use of two or three layers of expanded sheets.
The preferred range ~or the load bearing capacity is in the from about 2~0 Ib. per sq. foot to about 2000 Ib. per sq. foot. At excessively high load bearing capacities, the expanded cushion ing D~aterial is too stiff to absorb impacts effectively and can be abrasive rather than giving.
When the filling material is wrapped around an articles, it is in the form of a plurality of layers of i~terlocked expanded sheets due to the land areas of adjacent sheets of ~e layers of sheets nesting and interlocll~ing ~th each other, thus preventing or at least restricting the con-traction of the expanded sheets.

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The filling material can be stored in stacks of sheets. Alternatively, it takes the form of is a single sheet in a` continuous roll. The roll can be formed of a plurality of layers of sheets, such that upon urlrolling, at least a pair of sheets are unrolled together. The parallel rows of slits are parallel to the machine direction of the continuous rolL thereby facilitatirlg the rolling '~
of the sheet during manufacture, without expanding after the forming of the slits.
The grain of the paper is preferably parallel to the machine direction of the continuous roll so as to provide ma~mum tear resistance, since it is difficult to tear across the grain, rather than between adjacent fibers.
Where the parallel rows of slits are transverse to the machine direction of the con~inuous roll, the sheet is expandable in the direction in which it is unrolled from the continuous roll, thus providi~g a handling convenience at the time of the wrapping process.
The pac3caging material can be restored to it original corlfiguration by applying opposing, contraction forces to the edges of the paper material which are not parallel to the rows of the slits, thus reversing the oper~ing action. The contracting force is applied at right angle to the force is was applied to expand the sheet. The paper can then be stored in a flat condition for future reuse.
RIEF DESCRIPTION OF THE DRAWINGS
The objects and advantagès of the instant inv~ntion will become apparent when the specifilcation is read in conjunctions with the drawings, wherein:
E;IGUlRE 1 is a top view of the slit sheet of the instant inverlltion;
FIGURE 2 is a perspective view of a stack of the slit sheets of FIGURE 1;
FIGURE 3 is a top ~qew of the expanded slit sheet of FIGIJRE 1;
FIGURE 4 is a ~oss-sectional view of a corltaines utilizing ~he slit sheets of FIGURE 1;
FIGURE S is a cross-sectional new of a container using the slit sheets of FIGURE 1 wrapped `¦ around an item;
FIGURE 6 is an enlarged, fragmentary top view of a slit sheet of paper;
FIGURE ? is arl enlarged~ fragmentary top view of the slit sheet of Figure 6 partially opened;
FIGURE 8 is an enlarged, fragmentary top view of the slit sheet of ~igure 6 opened;
~GVRE 9 is an enlarged, fragmentary top view of the slit sheet of Flgure 6 opened to ap-pro~amately 180 degrees;
FIGURE 10 is a side view of two of the raised cells of the instant invention; iri FlGURE 11 is a side view of an alter~ate embodiment of two of the raised cells of the insitant i~vention;
3 FIGURE 12 illusitrates the load v. deformatio~ eest ou unbound paper with a 0.078 thickness; ,:
FIC~URE 13 illustrates the load v. defonnation test on uIlbound paper with a 0.078 ehickness;
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WO 93/1891 1 PCI /US93/02~tS9 ~; ~ 3 S r) ~ 4 FIGURE 14 illustrates the load v. deformation test on unoound paper with a 0.078 thickness;
FIGURE 15 illustrates the load v. deformation test on bound paper with a 0.078 thickness;
FIGURE 16 illustrates the load v. deformation test on bound paper with a 0.078 thickné'ss;
FlGURE 17 illustrates the load v. deformation test on bound paper with a 0.078 thickness;
FIGURE 18 illustrates the load v. defonnation test on bound plastic with a 0.030 thickness;
FIGURE 19 illustrates the load v. deformation test on bound plastic with a 0.030 thickness;
Fl(~URE 20 illustrates the load v. deformation test on bound plastic with a 0.080 thickness;
FIGURE 21 illustrates the load v. defolmation test on bound plastic with a 0.û80 thickness;
FIGURE æ illuskates the load v. deformation test on bound plastic with a 0.040 thickness;
FIGURE 23 illnstrates the load v. deformation test on bound plastic with a 0.û40 thickness;
FlGURE 24 illustrates the relationship between FIGURES 15 and 18;
DETAILED DESCRIPrION OF l~E INVENTIC)N
In order to maintain cianty wiehiIl the instant disclosure, the defil3itions of specific terms have been induded herein. The definitions were obtained frorn Elements of Phvsics, G. Shortley and D. Williams, Second Edition, Prentice-Hall, Inc., Englewood Cliffs, NJ., 1~55.
Stress is related to the force causirlg deformation. Strain is related to the arnount of defor-mation.
Work is used in its technical definition. It is necessary for a force to act on a body and for the body to experience a displacement that has a component parallel to the direction in which the force is acting.
EneJgy is a measure of the capacity or ability of the body to perfonn work. It is a scalar quantity and is measured in the same urlits as work. The energy possessed by a body as a result of its motioll is c~alled kinetic energy. Ellergy possessed by a body as a result of its position or co~lguration is called potential energy. When referrîng to an elastic~body, the energy is referred to as ela~tic potential energy. The elastic potential energy of the cushiouing material is the amount of work the Gushionmg material can perform in absorbing the energy of the article.
Hookes Law - the deformation of an elastic body is directly proportional to the mag-~itude of the applied force, provided the elastie limit is not exceeded. The expanded material of the instant Lnvention does not exhibit a straight line relationship between the deformation and the mag~litude of the applied force. The relationship more nearly follo vs the cun~e which is characteristic of rubber, as shown on page 182 of Elements of Physics.
Elastic body is one that experie~lces a change in volume or shape when the deformiug forces act upon it but resumes its original si~ or shape when the deforming forces cease to act.
Elastic force is the force exerted by the body by ~rirtue of its deformation.

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Yield point, the point beyond stress when a large increase in strain occurs with almost no incsease in stress.
The strength of paper is measured by bursting, tear and tensile strength. Tear strength is '~
of significance in respect to the ability of the paper to resist having the slits tear during the ex- ~ `
panding operation. Tear resistance of paper is measured in accordance with TAPPI- T-414 om-88. This method measures the force perpendicular to the plane of the paper required to tear mul-tiple sheets of paper through a specified distance a~ter the tear has been started using an Elmendor~type tearing tester. ~n the case of tearing a single sheet of paper, the tearing resis-tance is measured directly. Tear resistance of the slits is greater transverse to the grain &ection than in the grain direction. This is due to the fibers having a lower resistance to being separated than to being broken or torn. Long fibers or highly oriented fibers will exhibit high transverse tear strengths but exhibit "memory' or a tenden~ to return to thelr initial position when bent.
Thus, a long fiber vir~ paper can provide high tear resistance, but an excessive tendency for the paper to reclose after the expansion step~ that is, to exhibit memory.
Tensile is the strength it takes to pull paper apart and is always in the opposite direction to the tear strength. The tensile strength i5 measured in accordance with TAPPI-T 494 om-88. A
paper with a 50% recycled Kraft with 40% VLrgin material pro~ides a tear strength, with the ~ain, of 240 grams and a oss direction strength of 120 grams. The mullen test showed a 100%
mullen. A 70 pound paper would, therefore, have a bursttng pressure of 70 pounds. The busting strength of ~ret:yclèd paper; with a post consumer content is 50% or 60% mullen. In a 70 pound sample :the bursting strength would be (.6 x 70) and a grammage of 112 grams per square meter.
The 70 pound paper pro~ides a tear strength of 96 grams in the machille direction and 120 gram in the oss diredion. The lensile strength is 6,792 grams per cent~neter l38 pounds per inch) in the machine direction and 3,39~ grams per centimeter (19 pounds per inch) in the cross direction.
For used with the instant inventioD, tear strength is of the great importance for resisting the ten-de~cy of the slits to tear under stress. Once the sheet of paper of the instant invention is ex-panded, the mullen or tensile streDgth has no impact upon the cushioning effect. Ri:gidity of the paper however, does have an affect on performa~ce. Have the grain structure orient predominant}y normal to the slits, has the advalltage of providing optimum tensile streng~h, tear ;
resistance and rigidity of the mclined land regio~
In one example a 60% recycled Kraft paper mixed with 40% virgi~ material was used to produce expandable sheet material. The tear strength in the direction of lhe grain w~
pounds aIld in the CIOSS direction 120 gr~ns. The paper showed a bursting pressure of 70 grams, (70 pound paper, 100% Mullen). The bursting stre~gth of recycled paper with a post ~onsumer ~ -content would typically have a S0 to 60% Mullen.

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3 ; ~~ 6 EXAMPLE I
A 70 pound natural Kraft paper was fed to a slitting unit for simllltaneously cutting all of the slits while the sheets are supported on a flat bed. The paper had the following ch~acteris-tics.
Weight 70 lb (about 68-74 wt range) thickness (caliper) 7.6 mils (range from 7.4 to 8.0 mils) Tensile - dry MD
(machine direction) 50 lbs/in (44 minimum) Tensile - dry CD
~' (transverse to MD) 20 pounds (18 minîmum) Moisture 5X
Tear Strength MD . 140 gms (130 minimum) Tear S~rength CD 160 gms (140 minimum) Mullen 55 psi ~50 minimum) Calendar 0 Nip Paper, whe~ it is manufactured, is put through a senes of calendar rolls, or ~ips" to flat-ten the top surface for printing purposes. Zero to eight r~ps will yield a ~ull~y, fibrous paper.
Eight nip5 produces a flat, noisy, hard surface paper The grea~er the nurnber of r~ips, the more fibers are crushed and the weaker the tear strength of the paper. The instant invention preferably uses a zero nip sto~k which keeps the fibers bulky and strorlg. This is advantageous when ~he paper is being open manualiy or without the spec:iali~ed machinery, described hereinafter. For use wi,th the spe~ed machinery, weaker paper is used, thereby increasing stiffness, overall yield and a more finished product. The ability to use ligl}ter paper is due to ,l the fact that the machinery opens the cells smooWy, everll,y, and due to the rollers, ,almost cell by cell, thereby reduciIIg the force needed to ope~ the cells. C)~ce the cells are opened, a variety of paper weights uill work well, depending UpOI the stiffness. Recycled paper, however, does provided the advantage that the shorter fibers have less ability to stretch ,alld ase therefore easier to open. t)bviously, the ;nore accurate the slitting of the paper, the easier the paper is to open. Recycling of paper results i~ the breaking of fibers and the reduced orientation of fibers during reprocessing. The breaki~g of fibers due to the recycling or as a result of embossing can at ar~ ex~reme, ultimately produce a tissue paper like softness. This degree of softness produces :? the minimum ,amour,lt of abrasion~ but little cushior~ing e~ect.
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WO 93/lB911 PCI/US93/02369 An essentially completely recycled paper can be used if the grain of the paper (the direc-tion of strongest strength) was opposite the direction of the slits. When the grain is in the sarne direction of the slits, it is difficult to open the paper and the paper tends to rip before opening.
While it would appear that the strength of the paper must be in the direction of expansion, what is actually required is adequate strength at the ~s of the slit, so as to prevent tearing of the slits. As the paper is expanded the forces that are placed on the paper are exered tangentially to the slit and increase as the paper is stretched. Recycled paper has less "stretch-ability" than vir-gin paper and is subject to ripping before it is fully opened if the direction of the grain is not used 90 degrees to the slit direction, a very weak recycled paper can be used, once it is opened because the hexagonal cells can be very stiff.
One means for measuring the ability of the expanded cushioning material to provide the required cushioning effect is the deforrnation capacity. That is, the amount which the expanded sheet material compresses under a load. A total deforrnation capacity of at least about 25% of its expanded thickness is preferred. Stated in another way, the expanded cushior~ing material can have a deformation capacity of at least about a twentieth of an inch per layer, under a load of about 500 pounds per square foot. In terms of the ratio of load to deformation, the expanded cusbio~g material advantageousIy has a deformation ratio of at least 40 psfl.Ol in of compres-sion over a deformation of at least .05 inch. Preferably, the expanded cushioning material has an average deformati raho of at least ~0 psf/.01 in of compression during a deforrnat;on of at least .1 illch.
The slit pape~ 10 is illustrated in Figure 1 as it would come off the machine. The fle~ble sheet 12 is preferably manufactured frorn exclusively recycled paper with the grain of the paper running in the direction of arrow A~ The fle~ble sheet L2 is provided with slits 14 and slits 16 which which are parallel to the edges 2~ and 24 of the flexible sheet 1~ and perpendicular to the paper grain~ The slits 14 and slits 16 are placed in rows and separated from one another by land 20~ The land 20 is a consistent size and pr~ides the support required to prevent the paper from tearing ~to strips whe~ opened. It is therefor necessary that the land 20 be of suificient size to prevent tear~g. ~he spaa~g between the individual s~its 14 and slits 16 must also be of suffi-cient size to prevent the paper from tearing. The off set positiorling of the rows of s~its 14 and slits 16 gives the paper resiliency when opened and is discussed in detail further herein. The ex-istence of partial s~its 14 and 16 at the ends 26 and 18 of the flexible sheet 12 do not ninder the efficie~cy of the slit paper 10 and allow the flexible sheet 12 to be p}oduced from roll paper '~
which is thell cut to the desirpd size. ~e sheet whe~n flat, lies in a frst plane. When expanded .

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WO 93118911 PCI/US93/02?~9 3`~rl 3-'3 8 ~J ---the expanded sheet is formed of cells 26 and land 20 areas, as illustrated in }~igure 3. Preferably, at least a majority of the land 20 areas lie in a plurality of parallel planes. The planes of the land 20 areas forrn an angle of at least about 45 degrees with the plane of the sheet in frat form.
The slitting operation in which the slits are cut into the sheet material can take several forms. In one embodirnent, rectangular sheets are provide with its total nurnber of slits in one action. The term rectangular should be understood to also include rectangles in which all four sides are e~ual, that is, square. Where the sheet material is subjected to rotary cutting or slitting, the pressure required for the cutting action is significantly lower that that which is reqnired for the flat bed cut, since essentially only a single row or a few rows of slits are cut sirnultaneously.
Where the slits aTe oriented in the machine direction, that is parallel to the direction of travel of the sheet ma~erial through the rotary cutter, the drawing force does not cause premature e~pan-sion. Unlike prior art structures and systems, expansion contemporaneous with slitting is not desirable. In this fashion, the sheet material has an effective thickness which is as much as one twentieth of the thickness of a sheet of expanded material. The compact configaration provides for the optimization of shipping and storage.
It is critical for optimum strength to place the rows of slits 14 and 16 perpendicular to the graill A of the paper. The construction o paper is such that the majority of fibers run in a single direction creating the grain which is the strongest direction of the paper. The placement of the rows of slits 14 and 16 perpendicular to the grain A places the strength a~ the alus of the slit. As ~he paper i5 stretched, the forces that are placed on the paper, arrive tangentially to the slits 14 and 16 and increase as the paper is stretched. Since the grain A prevents the sli~s 14 and 16 from tearing into the land 20, the slits 14 and 16 must be completely through the paper. Par-tial CUttillg of the slits 14 and 16 allows fibers to rema~ across the slits 14 aIld 16 and hinders complete opening of the slits 14 and 16 ard formation of the hexagons. The uncut fibers require greater force to open the ceUs 26 and will cause the cells to deform by changing the upward lift to a dowIlward one. The dow~ward positioning of the land 20 also inhibits the interlocking of the lattice effec~ when one sheet is placed on the other. This is due to the reverse angle of in-cline which pushes the sheets away from one another instead of interlocking.
Figure 2 shows the slit paper 10 cut a~d piled for shipping. Since the slit paper 10 is produced as flat sheets, a large quantity can be shipped in a relatively compact stack. As an ex-ample, paper having a thickness of û.OL5 inches creates a stack appro~mately 15 inches in heigh~, weig~ts appro~nmately 50 pounds and contains T7l sheets. The compact nature of this matenal allows for the equivalent of large qua~tities of other shipping materials to be shipped in very little space. The thickness ratio between the slit sheets 10 as they are shipped and after TlTlJTE SHEÇ~

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they are expanded is approximately 20 to 1. This allows a substantial cosi saving in shipping and storage. The filling space created by the expansion of the slit sheets 10 is appro~nmately æ
times that of the unexpanded sheet.
The slit sheet 10 can also be "flattened" after use to approximately its original form and can be then stored and reused several times. This saves not only in the cost of purchasing new materials, but an ecological savings in a tirne where everyone is conscious of this need.
The slit sheet 10 is shown in Figure 3, in an expanded state. The slit sheet 10 is expan-dable by sirnply pulling the opposing e~ds æ and 24 in the direction indicated by the arroY/s B
and C. The expansion of the slit sheet 12 opens the rows of slits 14 and 16 to form an array of hexagon cells 26. As the slit sheet h expanded, the spaces 20 are raised to form the sections 30, 32 and 34 fonning the two similar sides of each hexagonal cell 26 rotate upwardly and horizon-tally to form the raised padding effect. The quantity of land 20 between the slits 14 and 16 and the distance between the rows of slits 14 and 16 determine angle of the raised sections 30, 32 and 34. The greater the angle, the greater the support. The angle of the cells 26 allow the cells 26 to contact the object without ~e full abrasive force of a pure vertical ridged due to the ability to flex. The an~les created by the raised sections 30, 32 and 34 also sene to lock the slit paper 10 onto itself. The land ~0 assists in retaining the ~memory" of the paper, creating a pull affect as the paper tries to return to its original shape. A vertical ridge would retai~ the "memory" for a short period of time before retur~iug to its original position. Once the paper is returned to its original position, it loosens o~ the item, no longer providing the cushior~ing. The loclcing affect also allows for easy securing and makes taping optional. The incline of the land areas is less than g0 degrees9 and thus the object to be protected is subjected to significantly less abrasion than would be encountered if the objeat rested on a rigid support at ~0 degrees to its surface.
~: The land areas thus have a capacity to provide resi}ient, non-abrasive support.
The utilization of recycled paper, when the strength is properly utiL;zed, makes a very strong paclcaging medium onc it is opened. Recycled paper has less stret~h ability and is subject to tearing before it is opened if the graia A is not placed perpendicular to the rows of slits 14 ~:!, and 16. A recycled paper with a lower bursting strength can be used since once it is opened the ; hexagon cells can be made stiff e~ough to compensate for the tbi~ness. This stifflless can be al- -tered at the point of manufacture by the number of calendar rolls.
; Figure 4 illustrates one method of using the slit sheets 10 to pack an object 42. Slit sheets 10 have been e~anded and placed "~bled" within the container 48~ filling the co~tainer 48 ~ `
approxirnately 1\4 way. The object 42 is placed into the container 48 and additional slit sheets ~ 10 are expahded and crumbled, filli~g the open space 40 around a~d o~ top of the object 42. The : hexagonal cells 26 of the slit sheets 10 trap the air around the object 4~ providing additional sup-SU~STITUT SHEET

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WO 93/18911 PCl/US93/0~ 9 t port. The raised sections 30, 32 and 34 provide a non-rigid support which allows the object to remam unaffected by outside influences (recorded in the number of G's). As forces are applied, through vibration and impacts, the inner packaging of the instant invention although it w~U not collapse and flatten, does aUow some ~qeld, thereby preventing the object 42 from hitting a hard surface.
An alternative use of the slit sheet 10 is illustrated in Figure 5. A longer slit sheet 10 is used which has sufficient length to provide multiple wrappi~gs around the object 42. The slit sheet 10 is exp~ded to allow the raised sections 30, 32 and 34 to forrn the protective hexagonal cells 26. The slit sheet 10 i: wrapped around the object 42, in the direction of the arrows B and C, thereby forcing the continued expansion of the hexagonal cells 26 and allowing them overlap the layer below. The raised sections 30, 32 and 34 form a cushiornng affect and trap the air. A
sufficient number of sheets are used to fill the empty space 40 in the container 48. The interlock-ing ~rovided by the raised sections 30, 32 and 34 allow the next sheet to lock onto the previously wrapped sheets without the necessity of taping.
The preferred progression of open~g is illustrated in Figures 6, 7 and 8. Figure 6 il-lustrates the unopened slits 14 and 16 and more clearly illustrates the proportior~ between the slits 14 and 16 and the land 2~. The slit lengths 16L and 14L are maintained at an equal length throughout the cutting process. The slit spacing 36 between each of the slits 14 and 16 is also kept at arl equal distance as is the row spas~ing 38. The narrower the row spacing 38 the less land 20 which is forced to angle and the more hexagons whicll are ~eated. ConYersely, the greater the row spacillg 38, the greater is laIId area 20 and the fewer the cells 26. The degree of the angles is also controlled by the size of the row spaang 38, with the narrower spacing creating sharper angles. The slit spacing 36 has direct effect orl the ease of ope~i~g aIld the number of cells 26. Figure 7 illustrates the slits 14 and 16 in a partially ope~ed state. The cells 26 are nar- -row and the land 20 is not fully warped~ The slits 14 and 16 have been fully exte~ded in Figure 8, allowing a sli~tly less than 90% angling of the land 20.
As the cell 26 s~es increase, the qualiq of the cut is of greater importance. The larger the cell 26, the ~eater the defo~mity, until the deformity is to the point that the land 20 will lie flat around the edges of the grain instead of forming raised hexagons, as illustrated in ~igure 9.
The cells 40 have been stretched to their ma~mum and form squares or rectangles instead of hexagor c. ExpaDsion to this extent provides little or no cushior~ing effect by the land 42. The r ~eater the desired height, the cleaner and more complete the cut must be. To provide ~be proper nrpage, thc paper must move iO degrees to the suFtch dLeclio~ and simoltmoousb inense in ``.
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length. This causes a heavy load at each end of the slits 14 and 16 as they try to open in the op~ j posite direction, thereby reinforcing the need to place the grain A of the paper at right angles to the slits 14 and 16.
The length of the slit and the ratio of the land intervals between slit affects the dimen- r sions of the polygons which are forrned during the expansioll step. The high ratio of slit length to interval leng1h the greater is the ma~mum angle which can be formed between the plarle of the sheet and the planes of the la=d areas. I'he greater the uniformity of the shape and size of the formed polygonal shaped open areas and the angle to which the land areas incline relative to the flat sheet, the greater is the degree to which interlocking of land areas can be achieved. In-terlocking of land areas, that is~ the nesting of layers of sheets, reduces the effective thickness of the sheets. However, the net effect is still a drarnatic increase in effective sheet thickrless. For example, .008 inch thick paper having a slit pattern of a 1/2" slit, 1/16~ land by 1/8" row spacing can expand to about one quarter of an ~nch thickness and will have a net effective thicl~ness, whell nested, of about .375 inches.
The longer the slit relative to the rigidity of the sheet material, the weakerds the inter-locking effect and the cushioning effect due to the weakness of the expanded structure. A cell dimensiouing which results in a ma~nmwn expansioll to 100 % or rllore, of the unexpanded length results in excessive weakness of the expa~ded structure. If the slits are too small, expansion can be severely limited and cushior~ing can be excessively limited. This does not ~nean that the dirnensions are ~arrowly ~itica1, but rather that the dimension must be selected relative to th characteristics of the paper, as for example the degree of rigidity, and the cushioniDg or energy absorbing effects which are required. The resistance to expar~ion ill~eases relative to the in-crease in the size of the laIld areas. It should be understood that some resista~ce to oper~ing is desired. The object rests onr or contacts the edge of the sheet formed by the incline of the land areas which turns the perimeter of the openings into upper and lower edges.
Paper, unlike metal does not flow under pressure. That is to say that metal is ductile or malleable and ca~l be slit aI~d expanded without necessarily resulting ill land areas to rise to form all ir~cline with respect to the plane of the metal sheet. III this regard, at~ention is in~ited to U.S. Patent No. 4,089,090 which disdoses the forming of an expanded metal sheet ~thout a concomitant deaease in thè width of t~he sheet.
~s herctofore mentioned, the slit dillsensions can be varied to ease the process of openi}lg. 't A 5/8~ slit, 3/16" la~d by 3/16~ row opens Yery easily since the number of hexagons is reduced.
When the size of the hexagons are i~creased and the ~urnbers dec~eased, the stretched Lhickness was i~creased, produa~g a very viable wrap material. This s~g inc~eases the yield of the paper aIId pro~ides almost the sarne protectioll as the 1/2" slit. This suing provides a less expen-SU ~iTlTUTE SHEET

'l r.' WO 93/1$911 PCl/US93/02?s~9 ~;
J ~ 5~ ~3~ 12 sive product utilizing a larger content of post consumer waste while maintaining the integrity of the wrap product. The 1/2" slit, 1/16" land by 1/8" row pattern produces a more protective wrap due to the greater number of wraps that can be made within the same volume. Thus, a 21/2 pound vase ~ be protected from a thirty inch height with only 1/2" of land round the vase can be protected with the 1/~" slit pattern.
Figures 10 and 11 illustrate in more detail the raised effect of the slit sheet 10 through an end ~iew. The raised portions 60 are at an approximately 30 angle from the original plane.
The raised portions 60 represent a wider IOw spacing 38 than the raise portions 64 of Figure 11 The wider the row spacing 38, the more land which will be warped and the less the angle. The raised portions 64 of Figure 11 are at a greater than 45 angle and are created by use of a nar-rower row spacing 38. The greater the angle, the greater the warp and the less chance that the cells will close. I~se of the multiple layers, crea~ing the nesting effect, preYentS closure of the cells, making the angle of less importance irl general use.
The paper, once expanded creates semi-rigid peaks or lands. These peaks are similar to a spring in that o~ce force is applied and removed, they ~11 return to their original positioning, providing their elastic limit is not exceeded. The elastic force created by the resistarlce of the paper fibers slows the acceleration of the force. The work performed by movement of the semi-rigid peaks as a force is applied by an article, is the elastic potential energy of the expanded ~ material.
,~ The graphs of Figures 12 - 17 show the load applied ~o the expanded sheets by a compres-sion plate, plotted against changes in thickness of the expanded material under load. The com-3 pression plate applies a force across the surface of ~he entire expanded sheet. The load applied as disiplayed in the graph is îndependent of the size of the material to which ~he load is applied.
Table II hereiDiafter shows the conversio~ from appEed load to load in terms of pounds per square foot. The test results described herein have been converted from total load per sheet to pou~lds per square foot in order to provide a means for comparison between sheets of dif~erent si~es. The first columu of TaMe I is the applied load, the second column defines the polmds per square feet of unçxpanded material and the third colurnn the pounds per square feet of ex-panded material. As evident from Table I, when determining the load bear~ng capacity reqnired to protect an item, it can be determined by square footage of either expa~ded or unexpanded - material.
The tests were conducted on roughly 19~ ill by 37.25 inch sheets. The length of the sheets included about 1.25 inches of uncut materiaL thus the slit region is slightly under 20 '~ inches by three feet. The sheets were expanded to four feet long, resultillg in an expanded sur-~ace area of about 5.5 square feet as compared to about 5 square feçt u~expanded. Moderate ex-~ ?
SI~IBST1TUTE SHEET
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WO~3/18911 P~/US93/02369 13 . !J 3 7 i 3 parlsion of the sheets yields an overall increase of about 1/3 in length while only yieldiIlg about a 10% increase in square footage due to the decrease in width. The sheets we~e capab]e of fur- ¦
ther expa~sion to roughly 60 inches, but were not tested at maximum expansion. The uniqueness in the invention lies in the cushioI~ing results achieved through as little as a 10% expansion in ;
surface area. This surface area increase accompanies the thickness ir crease. It is the thickness irlcrease of at least about I0 fold which produces the drarnatic cushioning effect. In the tests, the sheets were subject to an nitial load until stabilization was attained.
In ar alyzing the significance of the cushioning data, it should be understood that a block of concrete has a great load beariDg capacity but not the capacity to cushion impact, or very min-imal elasticity. To cushion impact, the object being protected must have its momentum gradually absorbed by the elasticity of the cushioning material as a abrupt stop will cause damage. Thus, there must be a significant, progressive deceleration of the object caused by the elastic force of the cushioning material's resistance to distortion. The greater the amount of work expended in continually absorbing the irnpact the greater the effectiveness of the cushioning. The work ex-pended is directly related to the elastic force of the cushioning material. The light weight paper of U.S. Patent No. 4,8327Z8 has little elastic potential ener~r due to the weakness of the less than 30 pound paper used in the illvention of the patent. It is noted that the weight of paper is in pounds of paper per thousand square feet prior to expansion. The slit pattern of this material perrnits an expansion by a~ amount greater than 100% of its une~panded length. This material caII exert only a slight amount of energy absorption during the deceleration of the article being protected, untit the rigid qualiq of the adhesive~matenal is encountered at which point the deceleration is excessive. Furthermore7 the material is used in a non-interlocking marner, and `-relies o~ adhesive for structural strength. The presence of a rigid adhesive is antagonistic to the requirements of a cushioning material. It is thus evident that this material cannot be used as a cushionihlg material. It is further noted that the material would crush under a slight force and thus would not be capable of protecting all article against repeated impact while in transit.
The expa~ded paper of the instant irlvetltion initially deforms thereby absorbing impact.
This is shown in Figure 16 wherein the chart illustrates the deformatio~ of the packing material using, a 41Q0 pound load. The paper gradually absorbs irnpact as the load presses downw~d until it reaches the elastic limit at point A. After stresses greater tha~ point A have been attained, the pacicaging material reaches its elastic limit ~nd no longer regains its origi~al form when the dis-tortion forces are removed. The material wilL o~ce the force reaches the elastic limits, distort. ~r ~s the s~ress is increased beyond the elastic limit, the yielt point is reached and the fibers break, ~-however, as the elastic limit and yield point are so closely related and difficult to separate, both points will be referred to herein as the e~astic limit. Additional force se~ves to crush the struc-:j SU~;TITUTE SHEET

i 93/1891~ PCI/US93/02.~.~9 ture and the paper will reset itself at point B, providing some additional cushioning until point C
is reached, at which point little or no additional compression is produced with increasing load.
Typically, once the load/deforrnation point A is reached any absorption thereafter is ge~erally too rigid to provide required cushioning. Although the resetting, point B, can provide additional support or cushion, i~l the test described herein, this factor was discounted. As previously noted, `¦ once the elastic limit of the material is exceeded, the material loses its ability to provide further cushioning.
When used in multi-layers, additional benefits are encountered as the layers nest within `1 each under the load, providing increased distribution of the impact forces or energy absorption.
The nesting of the layers tends to affect the absorption characteristics of each layer synergisti-cally. In multiple layer systems, the cushioning effects of the curve region A-B can be substan-tial and each layor c~n have its load/deformation point A modified differently or independ-ently. The use of multiple layers, therefore, provides ma~mum cushioning effects.
`~ The benefit from the design of the expanded paper can be further appreciated when ~newed from the perspective of the dissipation oE impact forces. The ever expanding network of ~¦ strands within the paper absorbs and dissipates the energy of the article whose movement is being decelerated. Paper is comprised of multiple fibers unaligned to one ano~her, providing the equivalent of a nonwoven fabric. The nonaligned fibers force the object to engage many more `~ fibers upon impact, distributing the eIlergy along fiber axis to each interlacing point where it is dissipated. The binder in the fibers prevents the shock wave from pushing the fibers aside, providing a hi&her tran~latio~ efficiency. Ideally, a structure should &sipate irnpact energy rather than obstructing it. Fiber friction assist in absorbing energy by transfer~ing the force ~ created along the fibers. W~en used in multi- layers, an extensive three dimensional effect is Jl achieved as the` energy is dissipated simultaneously, in a pattern analogous to the ripple effect of ;?~
., a pebble droppe~i iDi water and fro~ layer to layer. The wave effect isi noted in to exist in each layer. The sheets of plastic as tested and shown in Figures 18 - 23, were relative nonelastic and without sllfficient elastic force to provide a significant degree of imipact absorption. Essentia~ly, the thin plastic film ~ailed to meet the minimumi threshold of load bearing capacity. Restated in ~`~ technical terms, the elastic limit and the elastic potential energy of the plastic film was inade-quate for the material to haYe utility as a cushioning material. Speci~lcally, a load bearing capacity of less than 100 lb. per square foot (psf) is inadequate to provide the minimum required ~--results. The use of multiple layers can of~set or mitigate the problems encountered ~Ath the low load bearing capaciq, but at tlhis level, an impractiicali mlmber of layers would be required, thus totally nullifying the utility of the expanded plastic material as a cushion~g material. Thus, the e~ ed plastic sheets of the type disclosed in U.S. patent 3,958,751 are inadequate ~o function ~: !
,~, 'i"
SUE~TITUT S~EET

3 1 ) as a packing or packaging material for cushion articles during shipping. At the other extreme, the expanded reinforcing sheet material of U.S. Patent No. 4,259,358, is far too rigid to function as a cushioning material. The material disclosed in U.S. 4,259,358 provides little elastiaty, thereby having rninimal elastic potential energy to cushion the aTticle. U.S. Patent No. 4,937,131 relates ~o cushioning dunnage materials. The term cushioning material, as employed herein, is consistent with the term as employed in U.S. Patent No. 4,937,131, the disclosure of which is in-corporated herein as though recited in full, for the purpose of providing definitions of terms and background as to the requirernents of cushioning products, or cushioning dunnage for use as packaging or packing materials.
The terln dunnage as used in the prior art, as for example U.S. Patent No. 4,937,131 and the patents cited therein, and the term cushioning material as used herein, means a material having sufficient irnpact absorptio~ capacity to protect an article in transit. Essentially, the cushioning material must be able to absorb the energy of the impact thereby averting damage to the article. The energr of the impact is typically expressed as the elastic potential energy.
Material such as disclosed in U.S. Patent No. 4,832,æ8 and 3,958,751, which have to be used in excessive thickness to provide some degree of cushioning due to low load bearing capacities, are not included within ehe term ~ushioning material. Moreover, these later material have such a low elastic limie that it coilld not be used to absorb repeated impact, as would be required to protect an article in tra~slt. For exarnple, if ie is necessary to fill a 64 cubic foot box with a material to protect a one pound article two inches i~ diameter by one foot long, the material is not i~cluded by the term dunnage or cushior~ing material.
At a minimum, a load bearing capacity of 150 Ib. per square foot, multiple layer is nor-mally required to produ~e the minimum required results. When light objects are being packaged or minimal handling problems are anticipated, at least two or three layers of expanded sheet material would be used.
At a load beanng capacity of 250 Ib. psf moderately delicate objects can be protec~ed by a reasonable ~umber of layers of expanded sheets. Typically, at least three layers are required fi~r delicate objects, at this minimurn level of layers.
At a load beanng capacity of about 300 Ib. psf an increase of applicability is noted. That is~ the 300 lb. psf level h~s significantly gè~er~l applicability.
At the load bearing capacity of about 400 lb. psf essentially universal applicability is ;,-reached, particularly due to the multiplier effect achieved with the use of a plurality of layers.
Another variab1e which has an affect upon the results which ci~ be achieved is the thick- `~
ness of the expanded paper. The use of greater expanded thickness per sheet can provide in- ~ .
creased elastic fc,rce, thereby ~creasing the resistance to force and raising the elastic limit. The . ! .

SUBSTlTUTE SHEET

~ ?' W0 93/1~11 P~/US93/~6g T::

use of multiple layers to achieve sequired thickness is prererred due to the nesting and locking `
interaction between adjacent layers and the enhanced distribution of impact forces between ested layers. The upper limit is not narrowly critical, except of course, excess rigidity is~coun-terproductive. Load bearing capacities in excess of 2000 Ib. psf per layer, ase indicative of rigid ,--materials which typic~lly are excessively abrasive with a low elasticity. In the preferred embodi-ment, the load bearing capacity would be i~ the range of 500 to 1500 psf to provide optimum elas-tic force. The use of rnultiple layers i~creases the amount of dissipation per pound which can ob-taiDed from the cushionmg system. Additionally, illcreased effective load bearing capacities can be achieved due to the significant amount of travel which is obtained at high loads.
Another way of evaluating the effectiveness of the cushioning effect relates to the slope of the curve of the line which represents load plotted ag~inct travel. When the curve is exces-sively steep mir~imal shock absorptior~ is present as the material shows little elasticity. Load bear-ing capacity is the ma~mum load which an expanded sheet can support before the slope becomes excessively severe. In the following tests, load bearing capacity is indicated as being the ma~-mum load which can sustained before the elastic limit is reached.
Expressed another way, an excessive slope is one which represents deceleration which is so severe as to provide inadequate shock absorption. Excessively shallow slopes are indicative of a material has too little elastic force, providing little or not resistance to the applied force. To overcome this laclc of elastic forcej or excessive elasticity, the material must be excessively thick to produce effect absorption of the force of an impact between object and expanded material.
Load beanng capacities in the range from about 250 to about 1000 Ib. psf should be compatible with the use of a reaso~able number of layers of expanded sheets, typically, two to four layers of expanded sheets.
ln terms of travel of material, thc expanded sheet should have a total tefonnation capacity of at least about 2~% of its expanded thickness. The deformation is preferably at least about a twentieth of an inch under a load of at least about 500 psf. A deformation of at least a twentieth of au inch under a load of at least about 2~0 psf provides extremely effective results.
Load bearing capacities ill excess of 3000 psf e~erld the scope of useful applications of the expanded sheet cushioning material.
As shown in the graph of Flgure 1~, the primary deformation takes place over a compres-sioll dista~ce of about .180 inches. under a load of about 5125 pounds. It is noted that at the load of ~125 the sheet rapidly collapsed, then resumed compressing progressively over a distance of , about .05 in~ Ac stated, the second stage of compression tends to be too severe in terms of load ~llBg~l ~ U, F ^~IJ'-E~

:l i , WO 93/18911 J ~ fJ ~ 3 Pcr/usg3/o236g i~ I
., i psf per inch of compression and therefore was not considered in evaluati~g the materials described herein The first stage of compression is defined as the re~on in which significant Ioad bearing capacity is exhibited. ~ I
Compression tests were performçd on the following five (5) types of packaging cushioni~g materials:
Ouantirv Description _Thickness Mountin~ Means Paper 0.078 Unbound Paper 0.078 Bound 4 Plastic 0.030 Bound Plastic 0.080 Bound Plastic 0.040 Bound The materials were tested using the following data:
Preconditioning temperature: +23 +/- 3C
Preconditioning relative humidity: 50 +/- 5X
Preconditioning duration: 24 hours (minimum) Applicable specification: ASTM D642-90 Test machine: Fixed platen Direction of applied load: Top to bottom Machine speed: 0.5 inch/minute Test date recorded: Load deflection : inches) at yield strength (pounds) Equipment _ _ Manufacturer Model Compression Tester LAB 5250 Temperature/Humidity ATL Walk-in External Equipment Chamber Slîng Psychrometer Taylor . N/A
~ ~, ~ The test readouts where in total pounds o~ compression force under a platen. The total square footage of a sheet of expandable material changes as the sheet is expanded to its maxi-mum expansion 1ength. However, with respect to the scope of the inYention the 10% difference behveen lOOC psf and 900 psf is not significant. Thus, comparing the load bearing capacity be- 5 tween two sheets can be meaningful, eve~ if o~e sheet is fully expanded and the other sheet is ;~ partially expanded.
A summary of the testing results are shown below in Table I.
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SlJE3~;TlTUTE S5~EET
! ~ ~

W O 93/18911 PCT/US93/0~9 , ~ 18 TABLE I
Test Yield Strength Displacement Number ~Yn~ (Inc'nes~
1 2475 0.155 2975 0.105 3 32~5 0.190 4 2412 0.140 2062 0.130 6 5150 0.190 7 ~125 0.1~0 8 4950 0.205 9 4100 0.190 2612 0.173 11 58/2~0 0.170 12 55/225 0.145 13 58/~75 0.160 14 :57jl5~ 0.140 55~175 0.215 16 55/l~0 0.230 17 57~175 0.260 18 55/210 0.230 l9 58j200 0.260 55/125 ~.085 21 ~59/125 0.120 22 60/150 0.140 23 .63/155 0.140 24 60/180 0.140 Test Numbers 2, 3, ~, 7,10,11,14~15,19, 20 and 23 have beeu included as Figures 12 - 22, respectively. ln order to avoid the use of an excessive number of Figures, all the results of all l[`est Numbers are identified above. For tests 11 through 24, two sets o numbers are included ~;-for the yield strength. The lower value is the point at which the material ~ushes arld the higher value is the ma~mum load.

SUBSTITUTE SHE~

19 r~ ?~ ,J i ~ ~ ~

Figure 12 ~ 14 illu~strate the results of tests performed on unbound paper with a 0.078 thickness. In Figure 12~ the elastic limit point A is reached at a weight of 2975 pounds with a dis-placement of 0.105 inches; in Figure 13 the elastic limit point A is reached at 3265 pounds with a displacement of 0.190 inches; and Figure 14 the elastic lirnit is 2062 pounds with a displacement of 0.130 inches. The unbound paper samples tended to return to their previous unstretched condi-tioll upon completion of the compression.
Figures 15 - 17 illustrate tests performed on bound paper with an 0.078 thickness. In Figure 15, the elastic limit point A is reached at a weight of 51~5 pounds with a displacement of 0.180 Lrlches; n Figure 16 the elastic lirnit point A is reached at 4100 pounds with a displacement of 0.190 i~ches; and Figure 17 the elastic lirnit is 2612 pounds with a displacement of 0.173 inches. The bound paper samples exhibited evidence of deformation upon completion of the com-pression testing.
Figures 18 and 19 illustrate test performed on bound pla~stic with a thickness of û.030. In Figure 18, the eiastic limit point A is reached at a weight of 58 pounds with a displacement of 0.170 inches and in Figure 19 the elastic lirnit point A is reached at 58 pounds with a displace-ment of 0.160 inches.
Figures 20 and 21 illustrate test performed o~ bound plastic with a thick~ess of OQ80~ In Figure 20, the elastic limit point A is reached at a weight of 57 pounds with a displacement of 0.140 inches and in Figure 21 the elastic limit poLnt A is reached at 58 pounds with a displace-ment of 0~260 inches.
Figures æ and 23 illustrate test per~ormed o~ bound plastic with a thickness of 0.040. In Figure æ, the elastic limit point A is reached at a weight of ~5 pounds with a displacement of 0.085 inches and in Figure 23 the elastic limit point A is reached at 63 pounds with a displace-ment of 0.14û inches.
The foregoing graphs of Figure 12 - 23 provide cun~es similar to those produced by rub-ber. The results which ma~y materials produce, according to Hooke's law, do not app}y with the slit materials in that it is not a straight line relatio~ship between elastic expaDsion and force ap-plied. This decrease of elastic orce must, therefore, be counteracted by the material used. As i ~ shown in the Figures, plastic has little elastic force, or resista~c~, to the pressure exerted. The paper of the instant inverltion, coun~eracts the decreased elastic force, slowi~g the deceleration of the object throu~h material resistaIIce. ~;
~igure ~4 illustrates the relationship between Figures 15 and 18. It illustrated clearly '-herein the cushioning affect of the plastic of line C does not approach the cushioning affect of tho instant invetltion, lillo D. , -~.' `I ~ U ~ T ~ ~ ~E~

i, WOf 93tl~911 PCI/US93/0~159 The correlation between the total pounds of load ~o load per s~uare foot of expanded `~1 material and load per square foot u~expanded, is pro~ide in the followi~g table.
'~ .

TABLE II
CONVERS ION TABLE
ABSOLUTE LOAD/SQ . FT . LOAD/SQ . ET .
LOAD UNEXPANDEDEXPANDED
~000 1200 1091 `'I 5000 1000 gog 4900 8û0 727 ~ 2000 ~00 364 `l 1000 200 182 ,,,,1soo 100 91 ~, ~j 300 60 55 200 ~0 36 -~-1~0 ~20 18 ~31 Commercially the wrappillg of an article can take the following sequence. Sheet matenal ';~ unrolled ~cm a continuous roll of matenal and expanded as it is used to wrap and enclose an o~ject. The sheet miaterial is then cut or rippeid from the roll and the wrapping action is com-pleted. In another embodiment, the material t,e fed from its roll to a second roll which is ro~at-ing at a rate whic~,i is higher than the peripheral speed of the f~st roll, thus stretching and ex-pan~ng the sheet material as it is being unrolled. l'his mechanism enables sheet material to be ,j opened to its ma~Qmum condition in which the hexagon expands into a recta~gular configura-tion. In the case of essentially cylindrical objects, such as liquor bottles, the sheet material ex-~'; tends be~ond the length of the bottle and contouss arouild the top and bottom oE the bottle thus fully enclosing the article.
~!

, ~
~6'' SLJE~STITUTE S~E~ET
, WO 93~18911 PCI/US93/02369 ~ `
21 ' ~ - . 7 i r~3 The slit sheets are manufactured at high speed by utilizing a modified rotary cutter in combination with conventional unwind and re-wind conventional. The rotary cutter utilizes two steel cylinders~ the upper containing a flywheel which contains the cut~ing edges. The ~ooden cutting die has been modified to contain kni~res mounted within precut slits found within the wood. In order to facilitate the addition of the modi~led wooden cutting die, and to make changing the damages knives easier, the upper cylinder is machined with a series of threaded holes to accommodate machined screws. A blocking mechanism is affLxed to the cylinder, through use of the screws, which holds the cutting knife in place. The lower cylinder is modified by adding a flexible surface referred to as a blanket. The blanket allows the knife from the upper c ylinder to pass through the paper and penetrate the surface of the blanket. This guarantees a cut lhrongh the paper and prevents the necessity of the cylinders having to be per-~ectly matched with eYen roundness and pressure.
The unwind and re-wind equipment allows the rolls of paper to be directly used, in a con-tinuous process, directly from the paper mill. The unwind allows the paper roll to maintain con-stant tension as the roll reduces its diarneter. A registered skid path is used on both sides of the rotary die cutter to maintain the paper in an even path. The re-wind uses tension to properly re-roll the finished goods or can be by-passed to a sheeter that cuts the roll stock into the desired lerlgth.
lt is eo be understood that the filling material sheets of the present invention may be formed of any desirable and sliutable dimensions depending upon the hollow spaces to be filled in packaging materials. While the descriptio~ of the filling material sheet member of the present invention describes one ex~mple ~nth respect to size and thickness, this is not intended to limit tbe seope of the hlven~ion.

~1 r I ~--t ~ ' -i SU~STITUTE SH~ET
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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A flat extendible sheet material for use in forming an expanded cushioning material for protecting an object during shipping by filling spaces in a package, comprising: at least one sheet of flexible paper material; said at least one sheet having a plurality of spaced slits in a pattern characterized in that individual slits extend transversely from one end of said at least one sheet of paper material to the opposing end of said at least one sheet of paper material, each of said rows having interval spaces between consecutive slits; said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel row of slits; said flexible paper material and said slit pattern, in combination forming upon expansion in the direction transverse to said parallel rows of slits, an array of hexagonal openings, said openings being bound by land areas and leg areas, the ratio of the space between slits to the length of the slits producing land areas which are significantly large so that upon expansion it will produce a hexagonal opening, said openings being generally similar in shape and size, in a consistent, uniformly repeating pattern, said land areas being rotated an angle of at least about 45 degrees and less than 90 degrees from its unexpanded position; said slit pattern producing an expanded sheet having a load bearing capacity of at least 120 gms/ sq.
cm, a deformation capacity of at least about 1.25 mm under a load of about 250 gms per sq.cm of expanded material, an unexpanded thickness on the order of less than about 0.25 mm and an expanded thickness of at least ten time said unexpanded thickness, and a total deformation capacity of at least about 25% of the expanded thickness.

2. The flat extendible sheet material according to Claim 1 and characterized in that said paper material has an expanded thickness on the order of at least about ten times the unexpanded thickness of said sheet when expanded to about 130% of its unexpanded length, said slits are essentially straight lines on the order of about 10 mm long, said interval space between the ends of each adjacent slits being on the order of about one-fourth the quarter length of a slit and the space between the parallel rows being of the order of about 3 mm.

3. The flat extendible sheet material according to Claim 1, characterized in that said at least one sheet is a single sheet in an unexpanded continuous roll.

4. A method of protecting an object for shipping by wrapping and cushioning said object in an expanded sheet material, characterized in that said at least one sheet of extendible sheet material is a flexible, non-woven fibrous material, having a plurality of spaced parallel rows of individual slits in a slit pattern extending transversely from one end of the paper material to the opposing end of said at least one sheet, each of said rows having interval spaces between consecutive slits, said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel row of slits and characterized by the further steps of: (a) expanding a length of at least one sheet of an extendible sheet material by extending the opposing ends of said at least one sheet, to form at least one expanded sheet having an array of openings, said flexible, non-woven fibrous sheet material and said slit pattern, in combination, when expanded to at least about 130% of its unexpanded length, producing an extendible sheet and, wherein said flexible material is paper, said sheet being expanded to a thickness at least about ten times the unexpanded thickness of said at least one sheet prior to wrapping said object with said paper having an array of hexagonal openings, said openings being bound by land areas and leg areas, the ratio of the space between slits to the length of the slits producing land areas which are significantly large so that upon expansion it will produce a hexagonal opening, said openings being generally similar in shape and size, in a consistent, uniformly repeating pattern, said land areas being rotated an angle of at least about 45 degree and less than 90 degrees from its unexpanded position, (b) wrapping said at least one expanded sheet around an object such that land areas of successive layers of sheet material interlock, thereby deterring the unwrapping of the sheet material wrapped around said object, and (c) placing the wrapped object in a package.

5. The method according to Claim 4, characterized in that said at least one sheet is paper in a continuous roll and the grain of the paper is parallel to the machine direction of said continuous roll.

6. The method according to Claim 4, characterized in that said at least one sheet has a resistance to tear at each slit of a tensile strength perpendicular to each slit on the order of at least about 40 pounds.

7. An article wrapped in a protective cushioning packaging material comprising the combination of; an expanded cushioning material and an article, said material comprising, at least one sheet of flexible, non-woven fibrous sheet material, characterized in that said at least one sheet has a plurality of slits in a pattern of spaced parallel rows of individual slits extending transversely from one end of the paper material to the opposing end of said at least one sheet, each of said rows having interval spaces between consecutive silts; said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel rows of slits; said flexible, non-woven fibrous sheet material and said slit pattern, in combination forming upon expansion to at least about 130% of its unexpanded length in the direction transverse to said parallel rows of slit, an array of hexagonal openings, said openings being bound by land areas and leg areas, the ratio of the space between slits to the length of the slits producing land areas which are significantly large so that upon expansion it will produce a hexagonal opening, said openings being generally similar in shape and size, in a consistent, uniformly repeating pattern, said land areas being rotated an angle of at least about 45 degree and less than 90 degrees from its unexpanded position, an article, said flexible sheet material being extended and wrapped around said article, whereby said article is wrapped in a protective cushioning packaging material.

8. The article according to Claim 7, characterized in that material is paper having a thickness of the order of less than about 0.8 mm and an expanded thickness of the order of at least about ten times the unexpanded thickness of said paper.

9. The article according to Claim 7, characterized in that said fibrous material is recycled paper having an average fiber length which is substantially less than that of unrecycled paper.

10. The article according to Claim 9, characterized in that said fibrous material is recycled paper having an average fiber length which is substantially less than that of unrecycled paper and which has a substantially lower grain orientation than that of unrecycled paper, whereby said paper has a lower orientation memory and has a lower tendency to return to the unexpanded configuration than that of unrecycled paper.