US2896692A - Method of making cushioning paper - Google Patents

Description

` July 28 l959 c. vlLLoREsl 2,896,692

METHOD OF MAKING CUSHIONING PAPER Filed Nov. 22. 1954 4 Sheets-Sheet 1 Zweraow.- Cazzo ZZZZOHQQL',

July 28, 1.959 c. vlLLoREsx 2,896,692 v METHOD OF' MAKING CUSHIONING PAPER Filed Nov. 22, 1954 4 Sheets-Sheet 2 zNvENToR Cam/lo Villoresi BY Mw, Wham ATTORNEYS C. VILLORESI METHOD OF MAKING CUSHIONING PAPER July 28, 1959 4 Sheets-Sheet 3 Filed Nov. 22. 1954 C. VILLORESI METHOD OF' MAKING CUSHIONING PAPER July 28, 1959 4 Sheeis-Sheet 4 Filed NOV. 22. 1954 INVENTOR' (Jamil/0 V//ores ATTORNEYS METHOD F MAKING CUSHIONINGxlfAPER i Camillo Villoresi, Milan, i Italy, assgnorf -to Societa per Azioni Fabbriche Fiammiferi ed Alini,` Milan, Italy,

a corporation of Italy n f l Application November 22, 1954, Serial No. 470,469

7 Claims.` '(Cl. 15d-33.05)

This invention relates to formed papers forwrapping, packing, and display and other decorative purposes, and

their method of manufacture, and pertains moreparticj {lin cougaons as intthe basic form, and then pres-y ularly `to the type of papers which are corrugated, pleated, fluted, or otherwise preformed to l,impart rigidity and cushioningproperties. [The presentapplicationgisa continuation-impart .oftrny `copending application Serial Number 244049 'filed August 28 1951 now abandoned' i Lsider'ed perpendicular ito the horizontal plane of the p One of the common types of paper used `for protective packaging is that ordinarily known as.,,singleffaced corrugated paper and consists of a corrugatedsheet attached `toa at backing sheet. Aplain` corrugatedsheet iii which the corrugations runin straightlinesin` the usual ,manner has verylittle ,rigidityor resistance to crushing. The corrugations can be easilyf` flattened, and the paperl can be readily pulled out straight inthe direction transverse to the corrugations. For thisreason` a flat backer is` ordinarily glued or pasted to one side `or to Iboth n, "sidesof a corrugated sheet in order tmretain the shape and position of the corrugations.` The ilaminatedsheet which is thus producedpis inelastic, and relatively'inexib le,vin all directions, anditsfuse isthu's limitedtopackragingat articles, forming boites, and other applications for which a stili, flat sheet is suitable.

Oneof the principal objects of this f vention isto provide la'cushioniiig paper `which,fin one of t's forms,A has `a rigidity and resistance ,to crushing'comparable, orisuperio'r'to that of the usual single-faced or double-faced corrugated paper ofjthe same weight; and, "in another form, "has a high degree gofrigidity infone fdireotion while being readily ilexible, extendiblle, and `elastic in'lanother direction so that it can be wrapped around 'circular or United Sie@ Patent@ tached. `QIIntthis form the -`paper is useful for protecting ftlat articles, for lining boxes, and for any of the other pur- (poses foi-which conventional corrugated paper is used. For many uses and applications, instead of having the "paperV completely rigid, that is, substantially inelastic "iiigboth` longitudinaland transverse directions, it is dei fsirable to have the paper flexible andr elastic in the longiftudinal direction, while still resistant to crushing in `a `directionApe'rpendicular to its general plane and stiffer in the transverse direction. Such form of the paper is ob l'tained by initially impressing the paper with the zigzag "ingor gathering the paper ina longitudinal direction so as tohbring the corrugations closer together in such 'reet'ony The"pressing of the corrugations results in an increase in the height or lvertical dimensions thereof, con-V paper and 'adecrease in the horizontal dimension 'or width, thus longitudinally of the paper, of the corrugatio'ns Tha-inclined faces of the zigzag undulations or cor'rugations` rotate aroundaxes `centrally intersecting the faces and paralleling transverse lines running alter- 'na'tely along the peaks and valleys of the corrugations, intermediate 'the points of the zigzags. The faces rotate about suchaxes, while moving bodily relative towards Aeach other about' the transverse lines. The zigzag `undulations'then appear somewhat flattened, as theylie on sloping `walls to either side of the transverse lines which serve as fold lines bu-t the angular formation has not been changed in actuality, the right angle Ofthezigl zag has` .not changed. In this forni, the paper is more ,resistanttowc'rushing, and stiffer in the transverse direc- ;tionqthan "inthe basic form, butl is liexible and elastic in the`1ongitudir1alzdirection.` Itis far superior in crush resistance andatransverse rigidity than,` for example, ordinary pleated paper, and has .the further characteristic f that it tends to spring back into shape after it is stretched irregularly shaped articles and will conform closely' to Vthe :1,

shape of such articles. t o y t i Another principal* objectof this invention is to"V provide a method of producing a'cushioning,paper'which-has the properties just described, and'whic'h permanently` retains these properties without a hackerrorvffac'irig'r sheet;u `Other' tionstm..corrugations` in parallel rows across the paper objects are to provide a` method of"permanentlyl impressing undulations into paper, and of subsequently .gathering the paper into folds running alongthef'general' direction of the undulations and compressing-the Efolds tjanydesired `degree of tightness according to the which are required for a particular purpose.

rIjhe paper here described, in` its basicffoini; hasits undulations disposed in zigzag lines, instead of the straight lines conventionally Aemployed in standardicorrugated pa- P91? Y' The. zigzag rows of unclulations` are preferably: of r p-ai-r of hated coopemtngorous each ofwhich has pe uniform width and their mean course is disposed along parallel lines running in adirectiongwhichgwillrbe `here referred fto as the trans'versef direction of the paper. The Adirection in thel general plane o flthe. paper per- Pmdizular to the transverse direbon wm @gemid 1 i' enoughy to maintanthe `paper straight. The paper has as the longitudinal directiorifVv Iii the, fbasicform the paper is highly resistant tocrushing in a vdii-ee on' perpendicular to 'its general yplarrteftis substantially `inelasticnin bothlongitudinal V'andgtrafnoverste directions, l'an o resistant to |buckling or bending n the transverse tio- It is moderately flexible thatait safb beat on a fairly large radius, inthe longitudinal direction, `but its rigidity, without abaclting sheet, neye'rthelesscomlparable to that of conventional corrugatedpaper formed from the same type of stock, with"a"backing`sheet at# ,direof the one roll and the papertravels between the roll and properties 5` 2 in the longitudinal direction, that is, about the transverse fold llines. In this form, the paper is an excellent cushioning wrapperfor round or irregularly shaped articles, as `it conformsfreadily tothe contours of such ar.ti 1e.S-v t H A t f v V The process is carried out in one 'or more stagesor steps, there being ve stages here described. The first A sta-ge,` whichfis.essential` ,for making the tbasicform of the papencomprises lthe impressing of zigzag undulawitna predetermined spacing arrangement. As used herein,` Athe words undulations and corruga-tions are synonymous, and `refer `to and describe the formations Y termed ffbas-reliefs. my ,aforesaid co-pending applica:- tion, the te'rn1"basreliefs. being also synonymous with the words undulations and corrugationsf Y ,n {Illicl pression: primarilyI a `heat molding `proces rather than a stamping or embossing process and is car-,

ried outby AtheluseA of an apparatus which includes a a? natural small moisture `content and passes` between the meshing teeth of the rolls and around a substantial part of the circurnferenceof4 one ofthe rolls. Arcurvred plate or shield is disposedabout the part of the circumference the plate or shield which is slightly spaced from the roll; It isbe,li`ev,ed that .a permanent set, is made in the paper `becauseof theheated meshing teeth and thefproitim'ity l, of Lthe paper to one of rolls'` following the meshing'i'ntefeth engageineutof the paper and ythat the moisture il! paper forms steam under-"the initial contact of the paper with the meshing teeth, andthe steam'produces a"'bar`"` rier or spacer between the roll and the paper and between the -shieldand the paper. The shield prevents the 'paper from oxidizing while imparting 4a permanent fre# "silient set to the paper after the initial impression; had lbeen made by the meshing teeth.v 'The steam rising from the vpaper on the 'initial engagement of the paper with lthe `meshing teeth is: believed to be channeled bv the circumference of the roll and the shield to form an insulating barrier which protects the paper from the'roll-and "shield The shield, because of its close proximity'to the fpaper and vstructural arrangement thereof with the roll, excludes `from contact with the sheet of paper all air 'eiicept for the small amount ofv air whichmay enter. in vthespacebetween the sheet and the shield. This small residual amount of air is insutticient to support combustion, and, furthermore, as stated above, at least part of this` residual air is driven out by stearnemitterd from the ',paper. The substantial `exclusion of air and the insulat- .ing effect of the steam barrier, resultant from moisture in the paper, are believed to be factors in preventing scorch- .ing or burning of the paper. The shield forms a curing chamber 4with the upper roll and the steam in such chamber pushes out the air so as to prevent oxidation. The paper has the impressions molded therein in passing through the bite of the rolls; The heated rollsr in pressing the paper upset the fibers and alternate and reposition or realign them and the set or mold is curedV and made permanent by the passage of the paper throughv the cur- :ingv chamber. In such chamber, the steam rising from the -paper at the bite of the. rolls expandsand pushes out 'and .excludes air. yThe paper, thus, has the rows of corrugations permanently set therein and the rows are preferably so spaced `that straight lines can be passed transversely of the paper and centrally along the mean course of the peaks and troughs of the corrugations. Such lines serve in the othery stages ofthe process as fold lines aboutxwhich the paper is gathered. y l

In the second stage of the process the paper is longitudinally gathered with the paper folding about the fold lines and the corrugations being brought closer together in a longitudinal direction of the paper; I-n the third stage the folds or pleats are further compressed, each *fold being moved closer toward the otherbut without destroying the zigzag corrugations and, Vin `the fourth stage, the folds are compressed still further in a longitudinal direction to form a very-tight'succession of undulated folds. A fifth stage may follow the fourth stage and consists of stretching the paper in a longitudinal direction to obtain an intermediate degree ofv tightfness. Dependent on the desired nal characteristics of the paper, the various stages willl be employed and all or any one of the stages subsequent to theirst stagemay be omitted.

t .Fig` l'lisaa planuview, somewhat enlarged, of the very tightly. folded product produced by the rst four stages of the method;

Fig. l2- is an edge view ofy the paper shown in Fig. 11, drawn to the samescalefas Fig. 7;

Fig. 13 is a schematic plan view of a small piece of the product shown in Fig; 1l; -f Fig. l'4 is'a schematic view of apparatus for carrying loutthe4 fifth stage as well as the first four stages of the Process; Y Fig .,l5 is an enlarged longitudinal section ofV a modification'of the paper produced by the rst stage.

. Fig'l' is an enlarged plan rview of the modicatin of rig. 15; j e

Fig. 17, is a side view of a bottle wrapped in the'ela'stic formof the paper;

Fig.V lj8 is a top. plan view of the paper product inl its basicform and is similar to, but on a larger scale than Fig. 16; i' s Fig. 19 is a longitudinal sectional view taken on line V19a-19 of'Fig. 1,8;

`Fig.`2():is a longitudinalsectional view similar to Fig'.

19 but showing the paper in a transitional stage between the tirstjstage and the "second stage or repressing step;-

Fig.'21 isA a longitudinal sectional view of the paper of Fig. ,18 after the, performance of the repressing step or thed emergence of the paper? from the second stage` of fthey method, thesection being taken on'a line at the` same point of the paper as Fig. 1 9; a 1

Fig. 22 is a longitudinal sectional view of the paper *after the second stage and is` taken on a line spaced trans- Y versely of the line on :which Fig. 21 is taken; and

In the drawings illustrating the best known form of the 1.

invention;

Fig. 1 is a schematic view of the apparatus used to carry out the irst stage of the process;

Fig. 2 is an yenlarged detail elevational view of a portion of the surface of one of the rolls and showing a typical tooth formation; Fig. 3 is an enlarged cross-section of a portion ofthe impressing rolls in the region of their meshing bite with the tooth portions of a pair of meshing discs shown in elevation; f Fig. 4 is a plan view of the basic form of the paper produced by the rst stage ofthe method;

s Fig. 5 is a cross-sectional view taken on line 5--5 of Fig.V 4; l

: ',Fig.w6v is a cross-section taken along line 6-6 of Fig. 5; f Fig. 7is a schematic view of suitable apparatus for l'carrying outthe second andthird stages of the process;

Fig, 2 3 is a longitudinal vsectional view of the paper after its emergence fromthe thirdstage.

The apparatus for performing the basic operation includes suitably internallyV heated, cooperating` impressing rolls :1,5- and lrandfa; shield 1 1 which is disposed around a substantial part of/theupper roll 15. The rolls are positively and synchronously driven in the direction of the arrows byany conventional means (not shown). These rolls areprovided with meshingv teeth havingchevron-like .-shape, as shown in Fig. 2, vThe rolls are preferably made upjofI sets of; disks arranged in pairs as, for example, disks 18`and, 19.v The pairs may be slightly spacedto provide grooves l20 which accommodate strip- .per fingers 2 1 and 22 at the bottom and top of the upper roll` The .paper sheet 23g is fed in the direction of the arrow 2,4 and passes between themeshing teeth ofthe rolls and around the upper roll until it emerges from the upper; edge of 'the shield plate at `the top ofy the upper roll.

` The paper ispr'eferably vfed at very light tension, the tension `being merely suiiicient to keep the sheet straight; the'paper is thus .gathered rather freely into the teeth which mesh fairlvloosely, as shown in Fig. 3. Preferably one of the rolls,l for example, the lower roll 16, is made `adjusta'l'rle up and down, so that the meshing clearance can be readily, variedv according to the thickness of the paper to be formed. The mesh is set very loose at the 'start of operations and afew trial sheets are run through. Therollsare vgradually brought into closer mesh until a trial' sheet appears uniformly impressed to the desired jdeptli. .'If themesh is too close, small cuts will appear in the paper indicating `that the rolls should be moved further` apart.- The temperature'of the rolls may lvary from about o C, to 480 C., according to the natv Ve of the paperrfedtof the machine.

assesses Figs. 4 and 18 is the result of a difference in the shape of the ends of the teeth. The teeth forming the corrugations of Fig. 4 are rounded somewhat at their ends while the teeth forming the corrugations of Fig. 18 have flatter ends.

The zigzag rows of corrugations 25 impressed in the sheet have a high degree of permanency and will retain,

their shape without a backing sheet. In the heavier kraft papers, for example, the corrugatons will spring back into shape after the paper is twisted or pressed a number of times. Even fairly thin papers, such as glassine, retain the impressionwith a considerable degree of permanency.

The rigid form of the product illustrated in Fig.` 4 and Figs. 16 and 18 can, therefore, be used in `place of the usual types of laminated corrugated paper for packaging liatarticles, lining boxes, and many other applications. The elimination of the`backing sheet and the pasting operation, which is required for making ordinary corrugated paper, makes this product very inexpensive.

1 Various kinds of paper, ranging, for example, from heavy kraft or strawboard to tissue and glassine, can be successfully treated by this process. Other materials, such as the various synthetic resin sheet materials, and paper backed metal foils which are widely used as wrappers can also be processed in this manner as can fabrics l and other materials. Any such papers or other material 'may be and preferably are fed to the machine in double ply or multiple ply.

:The rigidity and permanency of the corrugations impressed by the process just described appears to be due in part to the zigzag arrangement of the corrugations and in part to a heat molding effect which occurs. The reasons for the latter effect are not entirely understood.

It is believed, however, that the relatively long contact Yof the paper with the upper impressing roll, as compared tothe momentary contact which occurs in conventional corrugating and embossing operations, combined with .therelativelyhightemperature of the roll imparts a fpermanent se to the corrugations.` It has been found that the paper, in this process, will withstand temperyatures which would ordinarily cause charring and discoloration. This is due to the cooperation between the `roll 15 and the shield, thelatter performing three functions in association with the roll. First of all, the shield serves to guide the paper and is disposed close `enough -to `the roll so that the paper cannot spring away from theroll. The shield retains the paper in contact with Vthe 4heated roll throughout the length of the shield.

Secondly, the shield forms a channel with the roll and it excludes air from the channel and from the paper moving in the channel; Thirdly, since the paper has a natural small moisture content, steam is produced upon the pressure contact of the meshing teeth at the bite of the vrolls with the paper and this steam moves on both sides of the 'paper through the channel and is maintained by ftheperiphery of the roll 15 and the shield in contact with `the -paper to form an insulating barrier between the 'paper and the roll and between the paper and the shield. It is believed `that the air exclusion factor and steam `insulating barrier factor are the reasons why the possibility of oxidation is avoided. f; Theroll temperature required for performing the impressing operation depends on the type of stock to be processed and the speed at which it is run through. In general, the temperature should be as high as the stock will lwithstand without damage or discoloration. The ,optimum temperature for any particular material can be `the peaks and troughs ofthe `corrugations.

` `6 readily determined by running a `fewtest samples attthe desired operating speed, and varying the temperature until a satisfactory product is obtained. By way of example, a temperature of 325 C.` is suitable for kraft, chip, or straw paper run at feet la minute through rolls of about one foot diameter. This `temperature `is substantially higher than that heretofore used in corrugating or otherwise forming papers `of this general type.

As shown in Figs. 4 and 6, the zigzag corrugations are so arranged that the paper remains substantially straight along lines 26, which are the median lines: of the peaks r and along lines 26a which are the median lines 4of the valleys. 'Ihis arrangement is not essential `in the rigid form of the product. If the paper is to be vused in1the rigid form,1the zigzags of successive peak lines may over lap or may be spaced further lapart than in thefexample shown.4 Thel position `ofthe median lines,` however,` is

, important int'carrying out furthersteps in the process to produce the elasticform of paper, for the median lines serve as fold lines along which the paper is pleated. The' position of the median lines referred to above is shown more clearly inthe form of the rigid paper, 'illusltrated. in Figs. l5 land 16` and in Figs. l8,to.23. This `paper is produced in the manner already described, the

only` difference beingthat theroll teeth are cut with flatter ends, so that the resulting corrugations are trape- Vzoidal in cross-section, and the peak and trough regions appear as substantially llat zigzag strips. In Fig. 16, the numerals 40 refer to the peak or top strips, the numerals 41 to the trough or bottom strips, and the numerals 42 and 43 to the sloping side walls connecting It willv be noted that lines 26 pass. through the adjacent points of `the zigzag lines 44` and 45 which define the edges of thepeak strips 40.` These points will be referred toas `the inner vertices of the peak zigzags. `Lines 26a like- `wise pass through the inner vertices of the trough strips,

that is, the adjacent points of zigzag lines 46 and 47 which define the edges of the trough strips. The paper `can, be creased or folded readily only along the lines 26 and 26a as the shape of the corrugations presents considerable resistance to folding elsewhere. Thisis impor tant for the performance of further steps in theprocess which involve reversely folding, or pleating, the paper by gathering itin the longitudinal direction,l as the paper -willrtend to break evenly at such natural fold lines and fall `into uniform, even pleats. The paper need not lie absolutely straight along lines 26 and 26a but merely `straight enough so that the resistance to folding is small along the median lines `26 and 26a of the peaks and troughs as compared to other regions of the paper. In the form shown in` Figs. 4, 5 and 6, for example, in

`which the corrugations are of more rounded contour, `a

cross-section along one of the median lines, may appear slightly wavy, and consequently the fold lines ofthe pleats, as in Fig. 8 are slightly wavy. It is also apparent that the at peak and trough strips in the example of Fig. 16 might be slightly wider, in which case the median `lines would not pass through the inner vertices of the peak and trough zigzags. The paper would then not be constrained to fold alongvexact lines.: and. it is to be expected that the pleats resulting from further steps of theprocess would not be exactly even and uniform in depth.` As long as the transverse -folds are confined to fairly narrow regions, however, to produce the desired degree of uniformity in the pleats, the product would be usable for processing in the manner about to be described. `It is, therefore, understood that any reference herein to the lines 26 and 26a as lying substantially straight, oras running substantially through the inner vertices of the trough and peak zigzags, includes tolerable departures from the exact arrangement illustrated in Figs. 16 and 418 et seq.

" InFigs. 18 and 19, the paper is` shown in its basic formas shown in Figs. 15 and 16. T he llat top or` peak stnps40 extend transversely across the paper in longitudinally spacedrows and are spaced byA the sloping'side u-walls 42' and 43 `from the flat bottom or trough strips 41. The lines 26 and 26a pass through the top and bottom strips and form straightfold lines about which the top andbottont strips fold or roll as the side walls rotate `and move bodily toward each other. To describe this movement, attention is directed to Figs. 18' through 21, 1 wherein Figs. 20 and 21 are takenl on the-same line as Fig. 19 and-show the movement of the strips andthe side 1 walls. The lines 26 centrally intersect the top strips and dividethem into rows of staggered isosceles triangles .which-have their bases lying on the line 26. Thus, the I-triangles 40A bounded by the angular sections ofthe side walls42 have their bases lying on the lines 26 with the1triangles-40B bounded by the angular sections ofthe f side walls 43 having their bases on the; lines 26. The triangles 40B are in one row-in end toy end continuing relation at the lines 26 and the triangles 40A in the other row are in end tol end continuing relation at the lines '26. The sides of the triangles 40A are bounded'by the 'sloping angular sections of the side walls 42 and the sides orf the triangles 40B are bounded by the sloping angular 'sections of the side walls 43. The bottom strips are similanly divided into contiguous rows of triangles by the ymedian lines 26a. The lines 26 Yand 26a are thus prefV determined fold or hinge lines about which the contiguous rows of triangles rotate. For example, the row of "triangles 40A moves down about the line 26 while the row-of triangles `40A also moves down about the line 26, .until in a final stage, the rows of triangles 40A are vsubstantially vertically disposed alongside the vertically 'disposed rows of triangles 40B.

" This movement is accomplished by a gathering apparatus which gathers the paper longitudinally so that the 4paper folds about the lines 26 and 26a. The apparatus is shown in Fig. 7 and will be hereinafter described. With 'the apparatus of Fig. 7, the paper moves about the lines '26 and 26a into pleats or folds.

- As shown in Fig. 20, which is a transition stage between stage one (Fig. 19) and stage two (Fig. 21), the gatherv-ing action causes the paper to start to break on the lines v26 and 26a. The triangular section 40A moves down about the line 26 with the side wall 42B rotating about "itself and moving inwardly. The side wafll 43C moves inwardly toward the side wall 42B and rotates yabout Yitself. The bet-tom section 41D moves upwardly about 'the line 26a.

` The lines 26 and 26a form natural breaking lines or predetermined fold lines because the lines have the bases lof the triangles lying therein and the lines do not inter- .sect the apexes of the angular side Wall sections that bound the triangles. Thus, at such points, along the lines 26 and 26a there is less resistance to folding than -at any other points transverse of the paper.

In Fig. 21, the paper is shown as it appears after the completion of the second stage and it will be noted that the lines 26 and 26a form actual break lines. The ftriangles '40A and 40B have moved down about the Vline 26 and lie alongside each other on opposite sides of the line 26 but still retain their same angular shape. The side walls have moved closer relative to each other and have moved the triangles of the top stripinto parallel association with the corresponding triangles of the bottom strip which also retain their same angular shape.

In Fig. 23, which is a showing of the paper after the completion of the third stage, which is a tighter gathering or repressing stage, the triangles of the top strips and of the bottom strips have been very nearly turned from horizontal to vertical positions, that is perpendicular to the positions they occupied in Fig. 18 and the side walls have begun to nest together.

Fig. 22 is a view similar to Fig. 21 but taken at a point along the paper slightlyy spaced transversely of. Fig. 21. Irl-Fig. 22, the apexes of the triangles 40B-areV shown -the motion ofthe paper.

i are apart vertically.

` natural fold lines 26 and 26a.

ties.

while the points between thev triangles 40A are shown so 'that the walls 42B are fully illustrated;-

' In this respect, .-Figs. 20-23 are taken through-the apeXes of the triangles 40A and, therefore, through the points of touching connection of the triangles 40B- so that the side walls 43C are completely shownin association vwith the corresponding triangles 41D of the bottom strips.

It will be noted that the lines 26 are moved closer together longitudinally of the paper as are the lines 26a, while the lines 26 and 26a are moved furtherv apart vertically of the paper. The lines 2.6 are closer together in Fig. 23 than in Figs. 2l and 22 and the lines 26a are also closer together in Fig. 23 than inlFi'gs. 211 and 22.

The closer the lines are together is` dependent on the degree of' vrepressing or gathering andthe closer they; are

together, longitudinallyof the paper, the kfurtherthey The second step of the processis shown in Fig. 7:'.` The paper, as it emerges from between roll 15 and plate 1-7, passes over a plate 30, whichV may be an extension of the stripper ngers 22, and under a roll 27 whichl is Vdisposed above the inner end of the plate. TheV roll 27 is mounted on a swinging arm 28 which is spring pressed toward the paper, forlexample by. means of a spring 29. It is understood that any convenient means for mounting Ythe roll 27, andy applying yielding pressure to the roll,

in thelongitudinal direction, due to the fact that the .corrugations now lie on. the sloping sidesy ofthe pleats. ,The lines 26 and. 26a are broughtV closer together longitudinally of the paper Vwhile being moved further apart perpendicularly of the paper so that the overall thickness of the paperv has been increased. The paper. now appears as a series of pleats 33, with the initial zigzag. corrugations forming ripples 34 from` side to side along the sides of. each pleat. This. isv they basic elastic form ofv the product. In this form it. is highly exible. in

v.the longitudinal direction,` that isabout a. transversev axis,

but is very stiff in the transverse 'direction and considerably more resistant to crushing than the forrn of Eig; 4.

`In its elastic form-.the paper is highly suitable for Wrapping round, or irregularly shaped articles. For example, Fig.

1:7 showsa bottle wrapped in this form ofY paper'. The paper will stretch readily around the bulge of thebottle, and yet the stretched part retains its cushioning proper- The paper istruly elastic, rather than merely extensible, in the longitudinal direction, becauseitherippled structure imparted by the original zigzagl corrugations tends to draw the; pleats back into shape when the paper is-'released after stretching. This elasticity mayl also be due in part to the impression of the foldswhiley the paper is still, at high temperature.

Further stages of the processare directed to produce -varying degrees of tightness of the folds in the elastic Vform of the product.

The third step is performed` by means of a plate 31 which ismounted alongside of roll 27 and above plate 30.` Plate 3-1 is preferably mounted Vwith up and down adjustmentand is moved upout of 'contact with the paper, when only the rst. twoV stages of the process are being performed. Toperform thev third stage, plate 31 is brought down so that it' isspaced from 'plate 3 0 by a distance to barely clearthe paper4 as it emerges from roll 27.. Even though there is slight clearance, the movement of the paper will cause it` to drag slightly on one or the other of the plates. This slight drag will compress Vthe pleats in the longitudinall direction and increase the depth of the pleats suiciently so i that both plates will frictionally engage the paper. The

resulting product is shown in Fig. 23.

To perform the fourth stage of the process, a second spring pressed drag roll 35 ismounted alongside plate 31. This roll tends to crowd Vthe pleats between plates 31 and 30 so that they are further compressed in the longitudinal direction. The resulting product is a very tight, almost solid mass of pleats which still exhibit the ripples due -to the initial zigzag formation of the corrugations. The ripples of successive pleats are nested one within the other, as illustrated in the schematic view of two pleats shown in Fig. 13, and this interlocking effect imparts high rigidity to the product. This product is eX- tremely rigid in the transverse direction and Very diicult to crush, because of its solid structure, but it will still bend readily about transverse lines 26 and 2651, as shown by the reverse bends of the sample illustrated in Fig. 12. In Fig. 12 the paper is shown somewhat stretched for sake of clarity. Fig. 13 more nearly illustrates the structure in its relaxed condition.

The fifth stage is a stretching stage which is used to produce an intermediate degree of tightness. As shown in Fig. 14, the paper is fed to a pair of stretching rolls 36 which are positively driven in the direction of the arrows at a speed faster than the travel of the paper. The speed of the rolls may be varied to stretch the paper to any desired degree. A product of a tightness intermediate that produced by any of the preceding stages may thus be obtained. The fth stage may be employed immediately after the second, lthird or fouith stages, as desired.

In carrying out the process through any number of its stages, `two or more sheets of paper may be fed to the impression rolls at once, `to produce a laminated sheet. The laminations may, if desired, be secured together in the usual manner by paste or other adhesives. One of the interesting properties of this form of paper, however, is the fact that the laminations tend to interlock, due to the peculiar zigzag structure of the initial corrugations. This tendency is most pronounced in the tighter elastic forms of `the product. The laminations will thus cling together without adhesive, and the pasting operation can be eliminated for most purposes. 'This not only results in a saving but also Vmakes it possible to use colored papers of all kinds without danger of smearing and spotting. A wide variety of attractive two-color papers may be produced by laminating in this manner. These products are suitable for window displays, lamp shades, fancy wrappers, and a number of other uses.

I claim:

l. The method of forming a cushioning sheet material which comprises feeding a moisture-containing sheet of deformable material between a pair of intermeshing impression members heated toa temperature between 100 C. and 480 C., to form initially impressed parallel zigzag rows of corrugations in the sheet, moving the impressed sheet in continuing contact with one of said members through a confining channel immediately adjacent said one member, while maintaining the temperature of said one member Within said range, and simultaneously causing the formation of steam within said channel by evaporating the moisture of the heatedsheet therein, so that the steam confined in said channel tends to force air from the channel and from the depressions of said sheet, thereby to prevent scorching of the sheet and cause the initial impressions of said sheet to receive a more permanent set.

2. The method described in claim 1, wherein the sheet material is paper, the impression members are rotating rolls, and the paper sheet is relieved of tension while being fed to said impression rolls.

3. The method of forming a cushioning sheetmaterial which comprises feeding a moisture-containing sheet of deformable material between a pair of rotating intermeshing impression rolls heated to a temperature between C. and 480 C., to form initially impressed parallel zigzag rows of corrugations in the sheet, moving the impressed sheet in continuing contact with one of said rolls through a shielded confining channel immediately adjacent said one roll, while maintaining the temperature of said one roll within said range, and simultaneously causing the formation of steam within said channel by evaporating the moisture of the heated sheet therein, so that the steam confined in said channel tends to force air from the channel and from the depressions of said sheet, thereby to prevent scorching of the sheet and cause the initial impressions of said sheet to receive a more permanent set.

4. The method described in claim 3, wherein the sheet is then moved forwardly beyond said channel and away from said one roll, and the sheet is caused to be creased transversely on lines disposed along the troughs and peaks of the corrugations in the mean direction of the rows, by retarding such forward movement of the sheet.

5. The method described in claim 4, wherein said forward movement of the sheet is retarded by yieldingly pressing a drag roll against one surface of the sheet after it is moved away from said one roll.

6. The method described in claim 5, wherein the creased sheet is gathered and pleated by next moving the sheet between a pair of plates frictionally engaging opposite sides of the sheet, to retard its forward movement, and finally further retarding said movement by yieldingly pressing the creased and pleated sheet between a second drag roll and one of said plates, to compress its pleats, so that portions of adjacent rows of corrugations are nested together.

7. The method of forming a cushioning sheet material which comprises feeding a moisture-containing sheet of deformable material between a pair of rotating intermeshing impression rolls heated to a temperature between 100 C. and 480 C., to form initially impressed parallel zigzag rows of corrugations in the sheet, moving the impressed sheet in continuing contact with one of said rolls through a shielded confining channel immediately adjacent said one roll, while maintaining the temperature of said one roll within said range, and simultaneously causing the formation of steam within said Vchannel by evaporating the moisture of the heated .sheet therein, so that the steam confined in said channel tends to force air from the channel and from the depressions of said sheet, thereby to prevent scorching of the sheet and cause the initial impressions of said sheet to receive a more permanent set, moving the impressed sheet forwardly beyond said channel and away from said one roll, and causing the sheet to be creased transversely on lines disposed along the troughs and peaks of the corrugations in the mean direction of the rows, by yieldingly pressing a drag roll against one surface of the sheet after it is moved away from said one roll, to retard said forward movement, and then stretching the creased sheet in a direction at right angles to the creases thereof, to expand the sheet longitudinally.

References Cited in the file of this patent UNITED STATES PATENTS

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