WO1993018911A1

WO1993018911A1 - Packing material

Info

Publication number: WO1993018911A1
Application number: PCT/US1993/002369
Authority: WO
Inventors: Michael Hurwitz; David Goodrich
Original assignee: Recycled Paper Products Corporation
Priority date: 1992-03-16
Filing date: 1993-03-16
Publication date: 1993-09-30
Also published as: AU668148B2; EP0686089A4; CA2131713C; JPH07502718A; DE69322524T2; DE69322524T3; EP0686089A1; BR9306097A; ATE174261T1; HU9402503D0; ES2128421T5; JP2759846B2; EP0686089B1; HUT68990A; ES2128421T3; DE69322524D1; EP0686089B2; CZ223694A3; CA2131713A1; AU3809493A

Abstract

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

PACKING MATERIAL

BACKGROUND OF THE INVENTION 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 improved 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 wrapping objects for protection in moving are well known in the prior art. However, to date, 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 bulky and not generally feasible for home owners or some industries. Another disadvantage of existing filling materials is that they cannot be shipped in an unexpanded form thereby creating shipping cost based on bulk.

While the prior art devices provide improvements in the areas intended, none of the prior art overcomes the problems associated with general shipping. None of the prior art patents dis¬ close an environmentally safe material which can be wrapped around, and conform to, a delicate item.

The instant invention discloses a environmentally safe filling material manufactured from recycled paper in various sizes to meet the user's needs. The cushioning affect of the fill¬ ing paper is achieved through expansion at the time of use and therefore is shipped in an unex¬ panded form to provide an advantage for shipping and storage.

SUMMARY OF THE INVENTION

The present invention provides 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 non-woven fibrous material, preferably formed of biodegradable cellulosic fibers. .The use of 30 pound paper is preferred. Most preferably 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 than that of unrecycled paper, and conse¬ quently, a lower orientation memory and less of a tendency to return to the unexpanded con¬ figuration than that of unrecycled paper. The paper material preferably has a thickness less than about 0.03 inches and the thickness can be on the order of about 0.02 inches. Each sheet has, in its unexpanded 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. Each 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¬ ject 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 openings. Each of the openings are generally similar in shape and size and 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 twenty times the unex¬ panded thickness of the sheet. The opening action causes the land, or solid, sections between slits to bend in a direction normal 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 land areas lying in a plurality of parallel planes, forming an angle be¬ tween about 45 and less than 90 degrees (at full expansion) with the plane of the sheets, and preferably on the order of about 70 degrees.

The expanded cushioning material has a minimiim load bearing capacity of at least about 150 lb. per square foot of expanded material Preferably, the load bearing capacity is at least about 250 lb. per sq. foot. At a load bearing capacity of at least about 400 lb. per sq. foot, greater universality of application is achieved and optimum cushioning can be achieved in typi¬ cal applications with the use of two or three layers of expanded sheets.

The preferred range for the load bearing capacity is in the from about 250 lb. per sq. foot to about 2000 lb. per sq. foot. At excessively high load bearing capacities, the expanded cushion¬ ing material 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 interlocked expanded sheets due to the land areas of adjacent sheets of the layers of sheets nesting and interlocking with each other, thus preventing or at least restricting the con¬ traction of the expanded sheets. 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 unrolling, 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 facilitating 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 maximum 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 continuous roll, the sheet is expandable in the direction in which it is unrolled from the continuous roll, thus providing a handling convenience at the time of the wrapping process.

The packaging material can be restored to it original configuration 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 opening 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.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the instant invention will become apparent when the specification is read in conjunctions with the drawings, wherein: FIGURE 1 is a top view of the slit sheet of the instant invention; FIGURE 2 is a perspective view of a stack of the slit sheets of FIGURE 1; FIGURE 3 is a top view of the expanded slit sheet of FIGURE 1; FIGURE 4 is a cross-sectional view of a container utilizing the slit sheets of FIGURE 1; FIGURE 5 is a cross-sectional view 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 7 is an 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 Figure 6 opened; FIGURE 9 is an enlarged, fragmentary top view of the slit sheet of Figure 6 opened to ap¬ proximately 180 degrees;

FIGURE 10 is a side view of two of the raised cells of the instant invention; FIGURE 11 is a side view of an alternate embodiment of two of the raised cells of the instant invention;

FIGURE 12 illustrates the load v. deformation test on unbound paper with a 0.078 thickness; FIGURE 13 illustrates the load v. deformation test on unbound paper with a 0.078 thickness;

SUBSTITUTE SHEET FIGURE 14 illustrates the load v. deformation test on unbound 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 thickness; FIGURE 17 illustrates the load v. deformation test on bound paper with a 0.078 thickness; FIGURE 18 illustrates the load v. deformation 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; FIGURE 20 illustrates the load v. deformation test on bound plastic with a 0.080 thickness; FIGURE 21 illustrates the load v. deformation test on bound plastic with a 0.080 thickness; FIGURE 22 illustrates the load v. deformation test on bound plastic with a 0.040 thickness; FIGURE 23 illustrates the load v. deformation test on bound plastic with a 0.040 thickness; FIGURE 24 illustrates the relationship between FIGURES 15 and 18;

DETAILED DESCRIPTION OF THE INVENπON

In order to maintain clarity within the instant disclosure, the definitions of specific terms have been included herein. The definitions were obtained from Elements of Phvsics. G. Shortley and D. Williams, Second Edition, Prentice-Hall, Inc., Englewood Cliffs, ΝJ., 1955.

Stress is related to the force causing deformation. Strain is related to the amount 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.

Energy is a measure of the capacity or ability of the body to perform work. It is a scalar quantity and is measured in the same units as work. The energy possessed by a body as a result of its motion is called kinetic energy. Energy possessed by a body as a result of its position or configuration is called potential energy. When referring to an elastic body, the energy is referred to as elastic potential energy. The elastic potential energy of the cushioning material is the amount of work the cushioning material can perform in absorbing the energy of the article.

Hookes Law - the deformation of an elastic body is directly proportional to the mag¬ nitude of the applied force, provided the elastic limit is not exceeded. The expanded material of the instant invention does not exhibit a straight line relationship between the deformation and the magnitude of the applied force. The relationship more nearly follows the curve which is characteristic of rubber, as shown on page 182 of Elements of Phvsics.

Elastic body is one that experiences a change in volume or shape when the deforming forces act upon it but resumes its original size or shape when the deforming forces cease to act.

Elastic force is the force exerted by the body by virtue of its deformation. Yield point, the point beyond stress when a large increase in strain occurs with almost no increase 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 after the tear has been started using an Elmendorf-type tearing tester. In 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 direction 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 tendency to return to their initial position when bent. Thus, a long fiber virgin 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 is measured in accordance with TAPPI-T 494 om-88. A paper with a 50% recycled Kraft with 40% virgin material provides a tear strength, with the grain, of 240 grams and a cross direction strength of 120 grams. The mullen test showed a 100% mullen. A 70 pound paper would, therefore, have a bursting pressure of 70 poimds. The busting strength of recycled 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 provides a tear strength of 96 grams in the machine direction and 120 gram in the cross direction. The tensile strength is 6,792 grams per centimeter (38 pounds per inch) in the machine direction and 3,396 grams per centimeter (19 pounds per inch) in the cross direction. For used with the instant invention, tear strength is of the great importance for resisting the ten¬ dency of the slits to tear .under stress. Once the sheet of paper of the instant invention is ex¬ panded, the mullen or tensile strength has no impact upon the cushioning effect. Rigidity of the paper however, does have an affect on performance. Have the grain structure orient predominantly normal to the slits, has the advantage of providing optimum tensile strength, tear resistance and rigidity of the inclined land regions.

In one example a 60% recycled Kraft paper mixed with 40% virgin material was used to produce expandable sheet material. The tear strength in the direction of the grain was 240 pounds and in the cross direction 120 grams. The paper showed a bursting pressure of 70 grams, (70 pound paper, 100% Mullen). The bursting strength of recycled paper with a post consumer content would typically have a 50 to 60% Mullen. EXAMPLE I A 70 pound natural Kraft paper was fed to a slitting unit for simultaneously cutting all of the slits while the sheets are supported on a flat bed. The paper had the following characteris¬ 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 minimum)

Moisture 5%

Tear Strength MD 140 gms (130 minimum)

Tear Strength CD 160 gms (140 minimum)

Mullen 55 psi (50 minimum)

Calendar 0 Nip

Paper, when it is manufactured, is put through a series of calendar rolls, or "nips" to flat¬ ten the top surface for printing purposes. Zero to eight nips will yield a bulky, fibrous paper. Eight nips produces a flat, noisy, hard surface paper. The greater the number of nips, the more fibers are crushed and the weaker the tear strength of the paper. The instant invention preferably uses a zero nip stock which keeps the fibers bulky and strong. This is advantageous when the paper is being open manually or without the specialized machinery, described hereinafter. For use with the specialized machinery, weaker paper is used, thereby increasing stiffness, overall yield and a more finished product. The ability to use lighter paper is due to the fact that the machinery opens the cells smoothly, evenly, and due to the rollers, almost cell by cell, thereby reducing the force needed to open the cells. Once the cells are opened, a variety of paper weights will work well, depending upon the stiffness. Recycled paper, however, does provided the advantage that the shorter fibers have less ability to stretch and are therefore easier to open. Obviously, the more accurate the slitting of the paper, the easier the paper is to open. Recycling of paper results in the breaking of fibers and the reduced orientation of fibers during reprocessing. The breaking of fibers due to the recycling or as a result of embossing can at an extreme, ultimately produce a tissue paper like softness. This degree of softness produces the miniπnim amount of abrasion, but little cushioning effect.

SUBSTITUTE SHEET 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 same 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 axis 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 exerted 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 deformation capacity. That is, the amount which the expanded sheet material compresses under a load. A total deformation capacity of at least about 25% of its expanded thickness is preferred. Stated in another way, the expanded cushioning 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 cushioning material advantageously has a deformation ratio of at least 40 psf/.Ol in of compres¬ sion over a deformation of at least .05 inch. Preferably, the expanded cushioning material has an average deformation ratio of at least 80 psf/.Ol in of compression during a deformation of at least .1 inch.

The slit paper 10 is illustrated in Figure 1 as it would come off the machine. The flexible sheet 12 is preferably manufactured from exclusively recycled paper with the grain of the paper running in the direction of arrow A. The flexible sheet 12 is provided with slits 14 and slits 16 which which are parallel to the edges 22 and 24 of the flexible sheet 12 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 provides the support required to prevent the paper from tearing into strips when opened. It is therefor necessary that the land 20 be of sufficient size to prevent tearing. The spacing between the individual slits 14 and slits 16 must also be of suffi¬ cient size to prevent the paper from tearing. The off set positioning of the rows of slits 14 and slits 16 gives the paper resiliency when opened and is discussed in detail further herein. The ex¬ istence of partial slits 14 and 16 at the ends 26 and 18 of the flexible sheet 12 do not hinder the efficiency of the slit paper 10 and allow the flexible sheet 12 to be produced from roll paper which is then cut to the desired size. The sheet when flat, lies in a first plane. When expanded

SUBSTITUTE SHEET the expanded sheet is formed of cells 26 and land 20 areas, as illustrated in Figure 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 form an angle of at least about 45 degrees with the plane of the sheet in flat form.

The slitting operation in which the slits are cut into the sheet material can take several forms. In one embodiment, rectangular sheets are provide with its total number of slits in one action. The term rectangular should be understood to also include rectangles in which all four sides are equal, 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 required for the flat bed cut, since essentially only a single row or a few rows of slits are cut simultaneously. Where the slits are oriented in the machine direction, that is parallel to the direction of travel of the sheet material through the rotary cutter, the drawing force does not cause premature expan¬ 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 configuration 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 grain A of the paper. The construction of 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 at the axis of the slit As the paper is 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 slits 14 and 16 from tearing into the land 20, the slits 14 and 16 must be completely through the paper. Par¬ tial cutting of the slits 14 and 16 allows fibers to remain across the slits 14 and 16 and hinders complete opening of the slits 14 and 16 and formation of the hexagons. The uncut fibers require greater force to open the cells 26 and will cause the cells to deform by changing the upward lift to a downward one. The downward positioning of the land 20 also inhibits the interlocking of the lattice effect 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 and 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 0.015 inches creates a stack approximately 15 inches in height, weights approximately 50 pounds and contains 771 sheets. The compact nature of this material allows for the equivalent of large quantities 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 they are expanded is approximately 20 to 1. This allows a substantial cost saving in shipping and storage. The filling space created by the expansion of the slit sheets 10 is approximately 22 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 time 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 simply pulling the opposing ends 22 and 24 in the direction indicated by the arrows 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 is expanded, the spaces 20 are raised to form the sections 30, 32 and 34 forming 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 the full abrasive force of a pure vertical ridged due to the ability to flex. The angles created by the raised sections 30, 32 and 34 also serve to lock the slit paper 10 onto itself. The land 20 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 retain the "memory" for a short period of time before returning to its original position. Once the paper is returned to its original position, it loosens on the item, no longer providing the cushioning. The locking affect also allows for easy securing and makes taping optional. The incline of the land areas is less than 90 degrees, and thus the object to be protected is subjected to significantly less abrasion than would be encountered if the object rested on a rigid support at 90 degrees to its surface. The land areas thus have a capacity to provide resilient, non-abrasive support.

The utilization of recycled paper, when the strength is properly utilized, makes a very strong packaging medium once it is opened. Recycled paper has less stretch ability and is subject to tearing before it is opened if the grain 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 enough to compensate for the thinness. This stiffness 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 expanded and placed "crumbled" within the container 48, filling the container 48 approximately 1\4 way. The object 42 is placed into the container 48 and additional slit sheets 10 are expanded and crumbled, filling the open space 40 around and on top of the object 42. The hexagonal cells 26 of the slit sheets 10 trap the air around the object 42 providing additional sup-

SUBSTITUTE SHEET port. The raised sections 30, 32 and 34 provide a non-rigid support which allows the object to remain 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 will not collapse and flatten, does allow some yield, 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 sufGdent length to provide multiple wrappings around the object 42. The slit sheet 10 is expanded to allow the raised sections 30, 32 and 34 to form the protective hexagonal cells 26. The slit sheet 10 is wrapped around the object 42, in the direction of the arrows B and C, thereby fordng the continued expansion of the hexagonal cells 26 and allowing them overlap the layer below. The raised sections 30, 32 and 34 form a cushioning affect and trap the air. A sufGdent number of sheets are used to fill the empty space 40 in the container 48. The interlock¬ ing provided 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 opening is illustrated in -figures 6, 7 and 8. Figure 6 il¬ lustrates the unopened slits 14 and 16 and more dearly illustrates the proportions between the slits 14 and 16 and the land 20. 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 an equal distance as is the row spacing 38. The narrower the row spacing 38 the less land 20 which is forced to angle and the more hexagons which are created. Conversely, the greater the row spacing 38, the greater is land area 20 and the fewer the cells 26. The degree of the angles is also controlled by the size of the row spacing 38, with the narrower spacing creating sharper angles. The slit spacing 36 has direct effect on the ease of opening and the number of cells 26. Figure 7 illustrates the slits 14 and 16 in a partially opened state. The cells 26 are nar¬ row and the land 20 is not fully warped. The slits 14 and 16 have been fully extended in Figure 8, allowing a slightly less than 90% angling of the land 20.

As the cell 26 sizes increase, the quality of the cut is of greater importance. The larger the cell 26, the greater the deformity, 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 Figure 9. The cells 40 have been stretched to their maximum and form squares or rectangles instead of hexagons. Expansion to this extent provides little or no cushioning effect by the land 42. The greater the desired height, the deaner and more complete the cut must be. To provide the proper warpage, the paper must move 90 degrees to the stretch direction and simultaneously increase in

SUBSTITUTE SHEET lengthp.-This causes a heavy load at each end of the slits 14 and 16 as they try to open in the op¬ 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¬ sions of the polygons which are formed during the expansion step. The high ratio of slit length to interval length the greater is the maximum angle which can be formed between the plane of the sheet and the planes of the land areas. The 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 dramatic increase in effective sheet thickness. 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 inch thickness and will have a net effective thickness, when nested, of about .375 inches.

The longer the slit relative to the rigidity of the sheet material, the weaker is the inter¬ locking effect and the cushioning effect due to the weakness of the expanded structure. A cell dimensioning which results in a maximum expansion to 100 % or more, of the unexpanded length results in excessive weakness of the expanded structure. If the slits are too small, expansion can be severely limited and cushioning can be excessively limited. This does not mean that the dimensions are narrowly critical, but rather that the dimension must be selected relative to the characteristics of the paper, as for example the degree of rigidity, and the cushioning or energy absorbing effects which are required. The resistance to expansion increases relative to the in¬ crease in the size of the land areas. It should be understood that some resistance to opening is desired. The object rests on, 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 can be slit and expanded without necessarily resulting in land areas to rise to form an incline with respect to the plane of the metal sheet. In this regard, attention is invited to U.S. Patent No. 4,089,090 which discloses the forming of an expanded metal sheet without a concomitant decrease in the width of the sheet.

As heretofore mentioned, the slit dimensions can be varied to ease the process of opening. A 5/8" slit, 3/16" land by 3/16" row opens very easily since the number of hexagons is reduced. When the size of the hexagons are increased and the numbers decreased, the stretched thickness was increased, producing a very viable wrap material. This sizing increases the yield of the paper and provides almost the same protection as the 1/2" slit. This sizing provides a less expen-

SUBSTITUTE SHEET 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 2 1/2 pound vase can be protected from a thirty inch height with only 1/2" of land round the vase can be protected with the 1/2" slit pattern.

-figures 10 and 11 illustrate in more detail the raised effect of the slit sheet 10 through an end view. The raised portions 60 are at an approximately 30° angle from the original plane. The raised portions 60 represent a wider row 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 dose. Use of the multiple layers, creating the nesting effect, prevents dosure of the cells, making the angle of less importance in general use.

The paper, once expanded creates semi-rigid peaks or lands. These peaks are similar to a spring in that once force is applied and removed, they will return to their original positioning, providing their elastic limit is not exceeded. The elastic force created by the resistance 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 artide, is the elastic potential energy of the expanded material.

The graphs of Figures 12 - 17 show the load applied to the expanded sheets by a compres¬ sion plate, plotted against changes in thickness of the expanded material under load. The com¬ pression plate applies a force across the surface of the entire expanded sheet. The load applied as displayed in the graph is independent of the size of the material to which the load is applied. Table II hereinafter shows the conversion from applied load to load in terms of pounds per square foot. The test results described herein have been converted from total load per sheet to pounds per square foot in order to provide a means for comparison between sheets of different sizes. The first column of Table I is the applied load, the second column defines the pounds per square feet of unexpanded material and the third column the pounds per square feet of ex¬ panded material. As evident from Table I, when determining the load bearing capadty required to protect an item, it can be determined by square footage of either expanded or unexpanded material.

The tests were conducted on roughly 1925 in by 37.25 inch sheets. The length of the sheets induded 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, resulting in an expanded sur¬ face area of about 5-5 square feet as compared to about 5 square feet unexpanded. Moderate ex- pansion of the sheets yields an overall increase of about 1/3 in length while only yielding about a 10% increase in square footage due to the decrease in width. The sheets were capable of fur¬ ther expansion to roughly 60 inches, but were not tested at maximum expansion. The uniqueness in the invention lies in the cushioning results achieved through as little as a 10% expansion in surface area. This surface area increase accompanies the thickness increase. It is the thickness increase of at least about 10 fold which produces the dramatic cushioning effect. In the tests, the sheets were subject to an initial load until stabilization was attained.

In analyzing the significance of the cushioning data, it should be understood that a block of concrete has a great load bearing capadty but not the capadty 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 impact 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. 4,832,228 has little elastic potential energy due to the weakness of the less than 30 pound paper used in the invention 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 permits an expansion by an amount greater than 100% of its unexpanded length. This material can exert only a slight amount of energy absorption during the deceleration of the artide being protected, until the rigid quality of the adhesive material is encountered at which point the deceleration is excessive. Furthermore, the material is used in a non-interlocking manner, and relies on 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 cushioning material. It is further noted that the material would crush under a slight force and thus would not be capable of protecting an article against repeated impact while in transit.

The expanded paper of the instant invention initially deforms thereby absorbing impact. This is shown in Figure 16 wherein the chart illustrates the deformation of the packing material using a 4100 pound load. The paper gradually absorbs impact as the load presses downward until it reaches the elastic limit at point A. After stresses greater than point A have been attained, the packaging material reaches its elastic limit and no longer regains its original form when the dis¬ tortion forces are removed. The material will, once the force reaches the elastic limits, distort. As the stress is increased beyond the elastic limit, the yield 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 elastic limit. Additional force serves to crush the struc-

SUBSTITUTE SHEET 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/deformation point A is reached any absorption thereafter is generally too rigid to provide required cushioning. Although the resetting, point B, can provide additional support or cushion, in 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 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 layer can have its load/deformation point A modified differently or independ¬ ently. The use of multiple layers, therefore, provides maximum cushioning effects.

The benefit from the design of the expanded paper can be further appredated when viewed from the perspective of the dissipation of impact forces. The ever expanding network of strands within the paper absorbs and dissipates the energy of the artide whose movement is being decelerated. Paper is comprised of multiple fibers unaligned to one another, providing the equivalent of a nonwoven fabric. The nonaligned fibers force the object to engage many more fibers upon impact, distributing the energy 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 higher translation effidency. Ideally, a structure should dissipate impact energy rather than obstructing it Fiber friction assist in absorbing energy by transferring the force created along the fibers. When used in multi- layers, an extensive three dimensional effect is achieved as the energy is dissipated simultaneously, in a pattern analogous to the ripple effect of a pebble dropped in water and from layer to layer. The wave effect is noted in to exist in each layer. The sheets of plastic as tested and shown in Figures 18 - 23, were relative nonelastic and without sufficient elastic force to provide a significant degree of impact absorption. Essentially, the thin plastic film failed to meet the minimum threshold of load bearing capadty. Restated in technical terms, the elastic limit and the elastic potential energy of the plastic film was inade¬ quate for the material to have utility as a cushioning material. Specifically, a load bearing capadty of less than 100 lb. per square foot (psf) is inadequate to provide the minimum required results. The use of multiple layers can offset or mitigate the problems encountered with the low load bearing capadty, but at this level, an impractical number of layers would be required, thus totally nullifying the utility of the expanded plastic material as a cushioning material. Thus, the expanded plastic sheets of the type disclosed in U.S. patent 3,958,751 are inadequate to function

SUBSTITUTE SHEET 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. 4,259358, is far too rigid to function as a cushioning material. The material disclosed in U.S. 4,259,358 provides little elastidty, thereby having minimal elastic potential energy to cushion the artide. U.S. Patent No. 4,937,131 relates to 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 disdosure of whidi is in¬ corporated herein as though redted in full, for the purpose of providing definitions of terms and background as to the requirements of cushioning products, or cushioning dunnage for use as packaging or packing materials.

The term dunnage as used in the prior art, as for example U.S. Patent No. 4,937,131 and the patents dted therein, and the term cushioning material as used herein, means a material having suffiάent impact absorption capadty to protect an artide in transit. Essentially, the cushioning material must be able to absorb the energy of the impact thereby averting damage to the artide. The energy of the impact is typically expressed as the elastic potential energy. Material such as disdosed in U.S. Patent No. 4,832,228 and 3,958,751, which have to be used in excessive thickness to provide some degree of cushioning due to low load bearing capadties, are not included within the term cushioning material. Moreover, these later material have such a low elastic limit that it could not be used to absorb repeated impact, as would be required to protect an artide in transit. For example, if it is necessary to fill a 64 cubic foot box with a material to protect a one pound artide two inches in diameter by one foot long, the material is not included by the term dunnage or cushioning material.

At a minimum, a load bearing capadty of 150 lb. per square foot, multiple layer is nor¬ mally required to produce 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 bearing capacity of 250 lb. psf moderately delicate objects can be protected by a reasonable number of layers of expanded sheets. Typically, at least three layers are required for delicate objects, at this minimum level of layers.

At a load bearing capacity of about 300 lb. psf an increase of applicability is noted. That is, the 300 lb. psf level has significantly general applicability.

At the load bearing capadty 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 variable which has an affect upon the results which can be achieved is the thick¬ ness of the expanded paper. The use of greater expanded thickness per sheet can provide in¬ creased elastic force, thereby increasing the resistance to force and raising the elastic limit. The use of multiple layers to achieve required thickness is preferred due to the nesting and locking interaction between adjacent layers and the enhanced distribution of impact forces between nested layers. The upper limit is not narrowly critical, except of course, excess rigidity is coun¬ terproductive. Load bearing capadties in excess of 2000 lb. psf per layer, are indicative of rigid materials which typically are excessively abrasive with a low elastidty. In the preferred embodi¬ ment, the load bearing capadty would be in the range of 500 to 1500 psf to provide optimum elas¬ tic force. The use of multiple layers increases the amount of dissipation per pound which can ob¬ tained from the cushioning system. Additionally, increased effective load bearing capadties 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 against travel When the curve is exces¬ sively steep minimal shock absorption is present as the material shows little elastidty. Load bear¬ ing capadty is the maximum load which an expanded sheet can support before the slope becomes excessively severe. In the following tests, load bearing capadty is indicated as being the maxi¬ 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 lack of elastic force, or excessive elastidty, the material must be excessively thick to produce effect absorption of the force of an impact between object and expanded material. Load bearing capadties in the range from about 250 to about 1000 lb. psf should be compatible with the use of a reasonable number of layers of expanded sheets, typically, two to four layers of expanded sheets.

In terms of travel of material, the expanded sheet should have a total deformation capadty of at least about 25% 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 an inch under a load of at least about 2000 psf provides extremely effective results.

Load bearing capadties in excess of 3000 psf extend the scope of useful applications of the expanded sheet cushioning material.

As shown in the graph of Figure 15, the primary deformation takes place over a compres¬ sion distance of about .180 inches, under a load of about 5125 pounds. It is noted that at the load of 5125 the sheet rapidly collapsed, then resumed compressing progressively over a distance of about .05 in. As stated, the second stage of compression tends to be too severe in terms of load psf per inch of compression and therefore was not considered in evaluating the materials described herein. The first stage of compression is defined as the region in which significant load bearing capadty is exhibited.

Compression tests were performed on the following five (5) types of packaging cushioning materials:

Quantity Description Thickness Mounting Means

5 Paper 0.078 Unbound 5 Paper 0.078 Bound 4 Plastic 0.030 Bound 5 Plastic 0.080 Bound 5 Plastic 0.040 Bound

The materials were tested using the following data:

Preconditioning temperature: +23 +/" 3°C Preconditioning relative humidity: 50 +/" 5% 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

Sling Psychrometer Taylor N/A

The test readouts where in total pounds of 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 length. However, with respect to the scope of the invention the 10% difference between 1000 psf and 900 psf is not significant. Thus, comparing the load bearing capadty be¬ tween two sheets can be meaningful, even if one sheet is fully expanded and the other sheet is partially expanded.

A summary of the testing results are shown below in Table I.

SUBSTITUTE SHEET Test Number

1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Test Numbers 2, 3, 5, 7, 10, 11, 14, 15, 19, 20 and 23 have been induded as Figures 12 - 22, respectively. In order to avoid the use of an excessive number of Figures, all the results of all Test Numbers are identified above. For tests 11 through 24, two sets of numbers are induded for the yield strength. The lower value is the point at which the material crushes and the higher value is the maximu load. Figure 12 - 14 illustrate 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 limit is 2062 pounds with a displacement of 0.130 inches. The unbound paper samples tended to return to their previous unstretched condi¬ tion 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 5125 pounds with a displacement of 0.180 inches; in Figure 16 the elastic limit point A is reached at 4100 pounds with a displacement of 0.190 inches; and Figure 17 the elastic limit 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 plastic with a thickness of 0.030. In Figure 18, the elastic limit point A is reached at a weight of 58 pounds with a displacement of 0.170 inches and in Figure 19 the elastic limit point A is reached at 58 pounds with a displace¬ ment of 0.160 inches.

Figures 20 and 21 illustrate test performed on bound plastic with a thickness of 0.080. 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 point A is reached at 58 pounds with a displace¬ ment of 0.260 inches.

Figures 22 and 23 illustrate test performed on bound plastic with a thickness of 0.040. In Figure 22, the elastic, limit point A is reached at a weight of 55 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 0.140 inches.

The foregoing graphs of Figure 12 - 23 provide curves similar to those produced by rub¬ ber. The results which many materials produce, according to Hooke's law, do not apply with the slit materials in that it is not a straight line relationship between elastic expansion and force ap¬ plied. This decrease of elastic force must, therefore, be counteracted by the material used. As shown in the Figures, plastic has little elastic force, or resistance, to the pressure exerted. The paper of the instant invention, counteracts the decreased elastic force, slowing the deceleration of the object through material resistance.

Figure 24 illustrates the relationship between Figures 15 and 18. It illustrated dearly herein the cushioning affect of the plastic of line C does not approach the cushioning affect of the instant invention, line D. The correlation between the total pounds of load to load per square foot of expanded material and load per square foot unexpanded, is provide in the following table.

Commerdally the wrapping of an artide can take the following sequence. Sheet material unrolled from a continuous roll of material and expanded as it is used to wrap and endose an object. The sheet material is then cut or ripped from the roll and the wrapping action is com¬ pleted. In another embodiment, the material be fed from its roll to a second roll which is rotat¬ ing at a rate which is higher than the peripheral speed of the first roll, thus stretching and ex¬ panding the sheet material as it is being unrolled. This mechanism enables sheet material to be opened to its maximum condition in which the hexagon expands into a rectangular configura¬ tion. In the case of essentially cylindrical objects, such as liquor bottles, the sheet material ex¬ tends beyond the length of the bottle and contours around the top and bottom of the bottle thus fully endosing the artide.

SUBSTITUTE SHEET 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 cutting edges. The wooden cutting die has been modified to contain knives mounted within precut slits found within the wood. In order to facilitate the addition of the modified 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 affixed 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 cylinder to pass through the paper and penetrate the surface of the blanket. This guarantees a cut through the paper and prevents the necessity of the cylinders having to be per¬ fectly matched with even 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 diameter. 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 length.

It is to be understood that the filling material sheets of the present invention may be formed of any desirable and suitable dimensions depending upon the hollow spaces to be filled in packaging materials. While the description of the filling material sheet member of the present invention describes one example with respect to size and thickness, this is not intended to limit the scope of the invention.

SUBSTITUTE SHEET

Claims

WHAT IS CLAIMED IS:

1. An expanded cushioning material for use in packing or packaging comprising: at least one sheet of an essentially flexible, material; each of said at least one sheet having, in its unexpanded form, a plurality of spaced paral¬ lel rows of individual slits extending transversely from one end of the paper material to the op¬ posing end of said at least one sheet, each of said rows having interval spaces between consecu¬ tive slits; said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel row of slits; each of said at least one sheet being expanded by extending the opposing ends of each sheet which are parallel to the rows of slits whereby the slits form an array of openings, each opening being generally similar in shape and size, said at least one sheet in substantially expanded form having a suffident load bearing capadty and sufGdent elastic potential energy to protect an artide in transit against impact damage, by cushioning the artide.

2. The expanded cushioning material of daim 1, wherein said load bearing capadty is at least about 400 lb. per square foot of expanded material

3. The expanded cushioning material of daim 1, wherein said load bearing capadty is in the range from about 250 lb. per square foot to about 2000 lb. per square foot of expanded material.

4. The expanded cushioning material of claim 1, wherein said cushioning material comprises a plurality of layers of said at least one sheet of an essentially flexible, material, said plurality of layers having a load bearing capadty of at least about 400 lb. per square foot of expanded material.

5. The expanded cushioning material according to Claim 1, wherein said sheet material has an unexpanded thickness on the order of less than about 0.01 inches and said cushioning material has an expanded thickness on the order of at least about ten times the unexpanded thickness of said sheet.

6. The expanded cushioning material according to Claim 5, wherein said sheet material has an expanded thickness on the order of about twenty times the unexpanded thickness of said sheet.

7. The expanded cushioning material according to Claim 1, wherein said sheet material is biodegradable paper, and being substantially greater than 40 pound paper.

8. The expanded cushioning material according to Claim 1-, wherein said expanded cushion¬ ing material has a total deformation capadty of at least about 25%.

9. The expanded cushioning material according to Claim 1, wherein said sheet material is recycled paper having an average fiber length which is substantially less than that of unrecyded paper and which has a substantially lower grain orientation than that of unrecycled paper, whereby said has a lower orientation memory and has a lower tendency to return to the unex¬ panded configuration than that of unrecycled paper.

10. The expanded cushioning material according to Claim 1, wherein said sheet material is formed of cellulosic fibers.

11. The expanded cushioning material according to Claim 1, wherein said expanded sheet material is characterized by being expanded in the direction transverse to said parallel rows of slits by an amount on the order of at least about fifty percent greater than the length in said transverse direction of said sheet in its unexpanded form.

12. The expanded cushioning material according to Claim 1, wherein said sheet material has an expanded thickness on the order of at least about ten times the thickness of an individual, unexpanded sheet, said expanded sheet having an array of openings formed from said slits, each opening being a polygon of at least four sides and substantially of the same size.

13. The expanded cushioning material according to Claim 12, wherein said sheet lies in a first plane, said expanded sheet being formed of openings and land areas, at least a majority of said land areas lying in a plurality of parallel secondary planes, said plurality of parallel secondary planes forming an angle of at least about 45 degrees with said first plane.

14. The expanded cushioning material according to Claim 13, wherein said plurality of paral¬ lel secondary planes form an angle of less than 90 degrees with said first plane.

15. The expanded cushioning material according to Claim 14, said cushioning material com¬ prises a plurality of layers of interlocked expanded sheets, wherein at least a majority of said plurality of parallel secondary planes of adjacent layers are substantially parallel to each other.

16. The expanded cushioning material according to Claim 1, wherein said cushioning material comprises a plurality of layers of interlocked expanded sheets, wherein said the land areas of ad¬ jacent sheets of said layers of sheets nest and interlock.

17. The expanded cushioning material according to Claim 16, wherein each layer of said sheet material has an unexpanded thickness on the order of less than about 0.03 inches and an expanded thickness on the order of at least about ten times said unexpanded thickness.

18. The expanded cushioning material according to Claim 2, wherein said sheet material lies essentially in a primary plane, said expanded sheet being formed of openings and land areas, at least a majority of said land areas lying in a plurality of parallel secondary planes, said plurality of parallel secondary planes forming an angle of at least about 45 degrees with said primary plane.

19. The expanded cushioning material according to Claim 18, wherein said the land areas of adjacent sheets of said layers of sheets nest and interlock, and said expanded cushioning material has a load bearing capadty of at least about 400 lb. per square foot of expanded material.

20. The expanded cushioning material according to Claim 1, wherein said expanded cushion¬ ing material has a deformation capadty of at least about a twentieth of an inch per layer, under a load of about 500 poimds per square foot of expanded material.

2L The expanded cushioning material according to Claim 2, wherein said expanded cushion¬ ing material has a deformation ratio of at least 40 psf/.01 in of compression over a deformation range of at least .05 inch.

22. The expanded cushioning material according to Claim 21, wherein said expanded cushion¬ ing material has an average deformation ratio of at least 80 psf/.Ol in of compression during a deformation of at least .1 inch.

23. The expanded cushioning material according to Claim 19, has a load bearing capadty up to about 2000 lb. per square foot of expanded material.

24. The expanded cushioning material according to Claim 23, wherein said expanded cushion¬ ing material has a total deformation capadty of at least about 25%.

25. The expanded cushioning material according to Claim 24, wherein said sheet material is biodegradable paper, said paper being substantially greater than 40 pound paper.

26. The expanded cushioning material according to Claim 25, wherein said sheet material has an unexpanded thickness on the order of less than about 0.01 inches and said filling material has an expanded thickness on the order of at least about ten times the unexpanded thickness of said sheet.

27. The expanded cushioning material according to Claim 25, said sheet material lies essen¬ tially in a primary plane, said expanded sheet being formed of openings and land areas, at least a majority of said land areas lying in a plurality of parallel secondary planes, said plurality of parallel secondary planes forming an angle of at least about 45 degrees with said primary plane, at least a majority of said plurality of parallel secondary planes of adjacent layers being substan¬ tially parallel to each other.

28. The expanded cushioning material according to Claim 27, wherein said cushioning material comprises a plurality of layers of expanded sheets, wherein said the land areas of ad¬ jacent sheets of said layers of sheets nest and interlock.

29. The expanded cushioning material according to Claim 28, wherein said expanded cushion¬ ing material has a deformation ratio of at least 40 psf/.Ol in of compression over a deformation distance of at least .05 inch.

SUBSTITUTE SHEET

30. The expanded cushioning material according to Claim 29, wherein said expanded cushion¬ ing material has a total deformation capadty of at least about 25%.

31. An extendible filling material for use forming an expanded cushioning material for fill¬ ing hollow spaces in packaging or the like comprising: at least one sheet of flexible, non-woven fibrous material; each of said at least one sheet having a plurality 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 slits; said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel row of slits; each of said at least one sheet being expandable by extending the opposing ends of each sheet which are parallel to the rows of slits whereby the slits form an array of openings, each opening being generally similar in shape and size, said sliti; being essentially straight lines on the order of about one-half inch long, said interval space between the ends of consecutive slits being on the order of about three-sixteenths of an inch. the space between adjacent parallel rows being on the order of about one-eighth inch, said slits being arranged in a consistent, uniformly repeated pattern, said material being paper having a tensile strength on the order of at least about 40 pounds in the direction transverse to the direction of the rows of slits, the resistance to tear at each slit being on the order of at least about 100 grams, said fibrous material being recycled paper having an average fiber length which is sub¬ stantially less than that of unrecycled paper and which has a substantially lower grain orientation than that of unrecycled paper, whereby said material has a lower orientation memory and has a lower tendency to return to the unexpanded configuration than that of unrecycled paper.

32. The filling material according to Claim 31, wherein said at least one sheet is in a con¬ tinuous roll.

33. The filling material according to Claim 32, wherein said at least one sheet is a plurality of layers of sheets in a continuous roll.

34. The filling material according to Claim 31, wherein said at least one sheet is in a con¬ tinuous roll and wherein said parallel rows of slits are transverse to the machine direction of said continuous roll, whereby said sheet is expandable in the direction in which it is unrolled from said continuous roll.

35. A method of protecting a object for shipping, comprising the steps of: wrapping and cushioning said object in an extended filling material, said filling material being at least one sheet of flexible, non-woven fibrous material; each of said at least one sheet having a plurality 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 slits; said slits in each row being positioned adjacent the interval space between consecutive slits in the adjacent parallel row of slits; expanding each of said at least one sheet by extending the opposing ends of each sheet which are parallel to the rows of slits whereby the slits form an array of openings, each opening being generally similar in shape and size, thereby forming a substantially ex¬ panded sheet having a sufGdent load bearing capadty and sufGdent elastic potential energy to protect an artide in transit against impact damage, by cushioning the artide.

36. The method according to Claim 35, wherein said paper material has a thickness on the order of less than about 0.03 inches and said filling material is expanded to a thickness on the order of at least about ten times the unexpanded thickness of said sheet prior to wrapping said object with said paper.

37. The method according to Claim 36, wherein said fibrous material is recyded 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 unrecyded paper, whereby said has a lower orientation memory and has a lower tendency to return to the unexpanded configura¬ tion than that of unrecyded paper.

38. The method according to Claim 36, wherein said fibrous material is formed of cellulosic fibers.

39. The method according to Claim 36, wherein said sheet is substantially restored to its un¬ expanded configuration by applying a contracting force .

40. The method according to Claim 36, wherein said sheet when flat, lies in a first plane, said expanded sheet being formed of openings and land areas, at least a majority of said land areas lying in a plurality of parallel second planes, said second planes form an angle of at least about 45 degrees with said first plane, at least one sheet being wrapped around said object such that land areas of successive layers of sheet material interlock, thereby deterring the unwrapping of sheet material wrapped around said object.

41. The method according to Claim 36, wherein said at least one sheet comprises a plurality of layers of interlocked expanded sheets.

42. The method according to Claim 36, wherein said at least one sheet is in a continuous roll and further comprising the step of serving and expanding a rectangular section of sheet material to form an expanded wrapping material, and wrapping said expanded wrapping material around said artide such that land areas of successive layers of sheet material interlock, thereby deter¬ ring the unwrapping of sheet material wrapped around said object.

43. The method according to Claim 36, wherein said at least one sheet is a plurality of layers of sheets in a continuous roll.

44. A article wrapped in a protective material comprising the combination of; an extended filling material, said material comprising, at least one sheet of flexible, non-woven fibrous material, each of said at least one sheet having a plurality of spaced parallel rows of in¬ dividual 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 consecu¬ tive slits, said slits in each row being positioned adjacent the interval space between consecu¬ tive slits in the adjacent parallel row of slits, each of said at least one sheet being expandable by extending the opposing ends of each sheet which are parallel to the rows of slits whereby the slits form an array of open¬ ings, each opening being generally similar in shape and size, the slit dimensions being such that each sheet can expand from at least about 50% to no greater than 100% of its unexpanded length, and an artide, said flexible sheet material being extended and wrapped around said artide, said at least one sheet having a sufGdent load bearing capadty and sufGdent elastic potential energy to protect said article in transit against impact damage, by cushioning the article.

45. The artide according to Claim 44, wherein said material has a thickness on the order of less than about 0.03 inches and said filling material has an expanded thickness on the order of at least about ten times the unexpanded thickness of said sheet.

46. The article according to Claim 44, wherein said fibrous material is recyded paper having an average fiber length which is substantially less than that of unrecyded paper.

47. The artide according to Claim 44, wherein said fibrous material is recycled paper having an average fiber length which is substantially less than that of unrecyded paper and which has a substantially lower grain orientation than that of unrecycled paper, whereby said has a lower orientation memory and has a lower tendency to return to the unexpanded configuration than that of unrecydqd paper.

SUBSTITUTE SHEET

48. The artide according to Claim 44, wherein said fibrous material is formed of cellulosic fibers.

49. The artide according to Claim 44, wherein said sheet lies essentially in a primary plane, said expanded sheet being formed of openings and land areas, at least a majority of said land areas lying in a plurality of parallel second planes, said plurality of parallel second planes form¬ ing an angle of at least about 45 degrees with said primary planes and wherein said land areas of adjacent sheets nest and interlock.

50. The artide according to Claim 49, wherein said plurality of parallel second planes form an angle of less than 90 degrees with said primary plane.

51. The artide according to Claim 50, wherein said filling material comprises a plurality of layers of expanded sheets which are interlocked by nesting.

SUBSTITUTE SHEET