US 2916411 A
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Dec. 8, 1959 c. VILLORESI COMPOSITE PACKING PAPER 2 Sheets-Sheet 1 Filed Nov. 3, 1955 Dec. 8, 1959 c. VILLORESI 2,916,411
COMPOSITE PACKING PAPER Filed Nov. :5, 1955 2 Sheets-Sheet 2 the corrugations.
United States Patent COMPOSITE PACKING PAPER Carnillo Villoresi, Milan, Italy, assignor to Societa per Azioni Fabriche Fiammiferi ed Aflini, Milan, Italy, a corporation of Italy Application November 3, 1955, Serial No. 544,797
Claims. (Cl. 154-55) This invention is general to the manufacture of corrugated paper and pertains more particularly to papers somewhat similar to the elastic type described in my copending application Serial No. 470,469, filed November 22, 1954, now Patent No. 2,896,692, but having improved and more permanent crush-resistant properties, as well as to methods and machines for manufacturing the improved paper.
Elastic paper of the type described in my aforesaid copending application is manufactured by first impressing a flat sheet of paper with zigzag rows of corrugations, by a hot impression process, and then pleating the sheet along the median lines of the peaks and troughs of the corrugations. In the finished paper the initially impressed corrugations appear as undulations to either side of the fold lines. This paper is both extensible and elastic in its longitudinal direction, that is, in the direction generally perpendicular to the initially impressed rows of corrugations. Due both to the zigzag configuration of the initially impressed corrugations and the permanency of impression imparted by the hot impression process, this type of elastic paper, even when stretched, retains substantial cushioning, or crush-resistant properties, as compared to ordinary corrugated paper, which can be readily flattened. It has been found, however, that the aforesaid elastic paper, when stretched to its fullest extent, does not retain sufficient cushioning properties or resistance to crushing for some packing purposes.
It is accordingly one of the objects of this invention to produce a packing paper which is flexible and, to
some degree, extensible, but which cannot be stretched to such an extent as to seriously impair its crush-resistant and cushioning properties.
Other objects are to provide a method and a machine for economically producing the improved type of paper described herein, in a continuous and automatic manner. Other advantages and novel features of the product, method, and machine here described will be apparent from the description which follows:
The paper consists, in general, of two sheets bonded together and both exhibiting, to some extent, the pleats andundulations which are characteristic of the elastic paper described in my previous application. One of the sheets, however, is pleated to less depth than the other and is bonded to the other only along the troughs of When the composite paper is stretched longitudinally, the sheet which is pleated to greatest depth cannot flatten out as it is restrained by its bond with the other sheet.
To form the composite paper, a flat sheet of paper is first impressed with zigzag rows of corrugations, preferably by passing it between a pair of heated toothed rolls and maintaining it in contact with one of the rolls around part of the roll diameter, as described in my previous application. While the paper is still on this roll, the outermost surfaces of the corrugations are coated with adhesive and a second flat sheet is then bonded to these surfaces. The two sheets then are pressed between two yielding surfaces, such as a flexible belt and a rubbercovered roller so that the flat sheet becomes slightly indented between its bonded regions, and finally the bonded sheets are compressed longitudinally, causing both to fold into pleats along lines corresponding to the median lines of the zigzag cor'rugtions originally impressed in the first sheet. Alternatively, the first sheet may be longitudinally compressed to some extent before the second sheet is bonded to it, and the two sheets further compressed after bonding.
In one form, the machine consists in general of a pair of heated impressing rolls, a pair of mating glue rolls, one of which rotates in a glue reservoir and the other of which transfers glue to the impressed sheet, a pair of bonding rolls through which the impressed, adhesive coated sheet and the flat sheet pass together, an endless belt arranged to press the combined sheets against a rubber-covered roller, and a drag roll and accumulator plate assembly adapted to compress the combined sheets longitudinally to impart the pleated eifect. In another form, the machine has a drag roll and accumulator assembly through which the first sheet passes on leaving the impressing rolls, and a belt and heated roll assembly which bonds the impressed and pleated sheet to the fiat sheet.
The processes and products to which this invention relates are described herein with particular reference to paper. It has been found, however, that many other flexible sheet materials, including, for example, plastic sheets, such as cellophane, metal foils laminated to paper, and fabrics, can be manipulated and formed in the same manner to produce products of similar characteristics. It will accordingly be understood that paper is referred to, in this description, merely as a typical example of the sheet material from which these products are manufactured and that the word paper as used in the following description and in the appended claims, is intended to include equivalent flexible sheet materials capable of being processed in the manner here described.
In the drawings illustrating the invention:
Fig. 1 is a longitudinal section, partly in diagrammatic form, of a machine for making the improved paper;
Fig. 2 is an enlarged detail cross-section of the belt and roll assembly between which the paper passes before entering the accumulator;
Fig. 3 is a longitudinal cross-section, somewhat enlarged, of a piece of the impressed sheet of paper, as first formed;
Fig. 4 is a bottom view of the improved composite paper as it appears after the fiat sheet has been bonded to the impressed sheet;
Fig. 5 is a longitudinal cross-section, somewhat en- ?rgegl, of the composite paper at the stage shown in Fig. 6' is a longitudinal cross-section of the paper of Fig. 4 after the final longitudinal pressing step;
Fig. 7 is a schematic side view of the finished composlte paper;
Fig. 8 is a schematic side view of the paper of Fig. 5 compressed in the longitudinal direction;
Fig. 9 is a schematic side view of the paper of Fig. :1 stretched to its fullest extent in the longitudinal direc- Fig. 10 is a longitudinal section, partly in diagrammatic form, of a modification of the machine; and
v Fig. 11 is a schematic side view of a modified form of the paper before the final longitudinal compressing step. e
I Fig. 12 is a schematic side view of the paper of Fig. 11 when completed.
In the machine shown in Fig. 1, the various working parts are mounted on a frame generally indicated by the numeral 20. The impressing rolls 21 and 22, supported on suitable bearings on the frame, are preferably constructed, as described in my aforesaid copending application, of a number of rings disposed side by side, having inclined teeth on their peripheries and arranged so that the teeth of successive rings slope alternately in opposite directions to produce a zigzag impression on the paper. The toothed surfaces of the impressing rolls are arranged to mesh. These rolls are internally heated, for example by means of electric heating elements 23 and 24, and are driven in unison through suitable gearing (not shown) in the direction of arrows 25 and 26.
Mounted alongside the upper impressing roll is a reservoir 27 for adhesive. A pick-up roller 28 is mounted to be partly immersed in adhesive in the reservoir, and
a transfer roller 29 is mounted to run in contact with roller 28 and with the paper passing around the upper impressing roll'.
A floating presser roll 30 is mounted immediately above impressing roll 22. To the right of roll 30 is mounted a plate 31, which is heated in any suitable manner, and a series of idler rolls 32 disposed above the plate. At the right-hand end of the plate is a curved guide 33. On the lower right-hand part of the frame are mounted a rubber-covered roller 34 and a series of belts 35 disposed side by side. The belts run over three idler rolls 36, 37, and 38, rolls 36 and 38 being placed so as to cause the belts to follow the contour of roll 34 around part of its periphery.
To the right of roll 34 is mounted the accumulator assembly consisting of a bottom plate 39, an intermediate upper guide plate 40, an upper plate 41, and a braking roll 42. Plates 40 and 41 are mounted with their bottom faces parallel to, and spaced from, the top surface of plate 39. Plate 39 is heated in any suitable manner. Braking roll is spring-pressed downward, and may be carried, for example, by a lever 43 mounted on a fulcrum 44 and restrained by a tension spring 45. Itoll 34 is driven, in any suitable manner, in the direction of arrow 46 at the same rim speed as rolls 22 and 23. The machine is preferably provided with an idle guide roll 47.
When the machine is in operation, two flat sheets of paper, designated A and B and schematically illustrated in Fig. 1, are fed continuously to the machine in any convenient manner, for example from ordinary supply rolls. Sheet A first passes around guide roll 47, through the bite of the impressing rolls, where the sheet is impressed with parallel zigzag rows of corrugations disposed perpendicularly to its direction of travel, and then up around the left half of roll 22. As the sheet passes around roll 22 those surfaces of the corrugations which lie outermost, which will be referred to arbitrarily as the bottom surfaces of the trough strips, are coated with adhesive by contact with transfer roller 29. Sheet B is fed directly between roll 22 and roll 30 and becomes bonded by pressure of roll 30 to the adhesive coated surfaces of sheet A.
After leaving roll 30, the bonded sheets pass over the heated plate 31 and the adhesive is dried. The sheets are held against this plate by the idler rolls 32. Thence the sheets pass down over the guide 33 and enter between roll 34 and belts 35. Roll 34 is preferably covered with a rubber soft enough to yield when the composite paper is pressed against it by belts 35. As a result, the portions of sheet B which lie between the trough strips of sheet A, become slightly indented as the bonded sheets pass between roll 34 and the belts, as illustrated in Fig. 2. On emerging from roll 34 the bonded sheets are confined between plate 39 and plate 40, and at the same time subjected to the braking effect of roll 42. As previously explained, paper formed in the manner of sheet A, when thus braked, or compressed longitudinally, tends to fold more or less sharply along the median lines of the peaks and troughs of the original rows of zigzag corrugations. Sheet B, having been predisposed to follow the general contour of sheet A by the indenting effect of roll 34, becomes slmllarly formed into pleats of the same pitch, or spacing, as those of sheet A, but having lower peaks. Plates 39 and 41 are so spaced as to drag slightly on the composite paper, and this further braking effect serves to press the pleats of the paper closer together in the longitudinal direction, while the heat of plate 39 tends to set the paper more permanently in its final form. On leaving the machine the finished paper may be passed to slitting or winding apparatus, as desired.
The process performed by the machine described above consists of first forming regular Zigzag rows of corrugations in a fiat sheet, coating the paper on one side along the outermost surfaces of these corrugations, bonding a second fiat sheet on to the coated portions of the formed sheet, slightly indenting the unbonded portions of the second sheet, and finally compressing the combined sheets in their longitudinal direction, or the direction perpendicular to the general direction of the rows impressed in the first sheet. I
The effect of these operations on the paper is illustrated in Figs. 3 to 6. The teeth of the impressing rolls used to form sheet A are so shaped as to form corrugations of generally trapezoidal cross-section with relatively flat peak strips 50 and trough strips 51, as shown in Fig. 3. As shown in Fig. 4, the rows of corrugations are so spaced and proportioned that the paper remains substantially straight along the median lines 52 and 53 of the peak and trough strips, respectively. These lines are natural fold lines along which the formed paper will fold into pleats, when compressed longitudinally, to form the elastic type of paper described in my previous application.
As shown in Figs. 4 and 5, which schematically illustrate the composite paper as it would appear just after leaving roll 30, sheet B is bonded to sheet A along the bottom surfaces of the trough strips 51. The bonded regions of sheet B are exemplified by the zigzag strips 54 outlined in dotted lines. These regions are separated by intervening zigzag strips 55 which are not bonded to sheet A. When the bonded sheets are longitudinally compressed, the peak strips of sheet A fold along lines 52 and the trough strips along lines 53. Regions 54 of sheet B fold, along with strips 51, about lines 53, while the unbonded regions 55 fold along lines 56 which are vertically in line with lines 52 but lie considerably below the peak strips 50.
The folding of sheet A in this manner imparts flexibility to the sheet, which, in the form shown in Fig. 3, is relatively rigid. The initial rows of corrugations are also brought closer together, imparting longitudinal extensibility to the sheet. The corresponding folding or pleating produced in sheet B makes this sheet also extensible, but to a lesser degree than sheet A.
Sheet A, as it appears in Figs. 3 and 6, corresponds, respectively, to the rigid and elastic type of paper described in my aforesaid previous application, the elastic type being derived from the rigid type. When paper of the said elastic type is stretched to its fullest extent, its initial zigzag impressions can be flattened relatively readily, or at least somewhat more readily than those of the rigid type. It is clear from Fig. 5, however, that the composite paper cannot be stretched beyond the point where sheet B becomes flat. At this point, sheet A has reassumed the configuration it had in Fig. 3, and is restrained by its bond with sheet B. The composite paper, therefore, cannot be longitudinally stretched to such an extent that its crush resistance is appreciably impaired.
F g 3, 5 and 6 are somewhat idealized to show distinctly theirelationship ofvarious'surfaces of theformed sheet A. It will be understood. that the peak and trough strips, and especially their edges, may appear more rounded in the actual product, and that the folds along lines 52 and 53 may also appear somewhat rounded, especially when sheet A is formed from relatively heavy stock such as straw or kraft paper of the grades commonly employed for packing. For purposes of considering the action of the paper as schematically illustrated in Figs. 7-9, the pleats may be regarded as equivalent to corrugations running straight across the paper, it being understood that the original zigzag corrugations of sheet A remain superimposed on these straight corrugations. Itwill also be understood that, as sheet A is the same in formation on both sides, either side may be considered as the top, or bottom, and sheet B is here described throughout as bonded to the bottom or the trough strips merely for consistency.
Fig. 7 illustrates schematically the finished composite paper in its normal or unstressed condition. It will be notedthat the pitch p, or distance between successive peaks of the straight corrugations of both sheets, is the same but that the peaks of sheet B are of considerably less height than those of sheet A. If the paper is compressed in the direction of the arrows in Fig. 8, the pitch of. these corrugations is reduced by the same amount on both sheets and the height of the peaks is increased, but the peaks of sheet B nevertheless remain spaced from those of sheet A. When the paper is stretched to its fullest extent, as in Fig. 9, the peaks of sheet B are fiattened out, but those of sheet A remain and merely return to the spacing and height which they had before sheet B was applied.
In the modified form of machine shown in Fig. 10, the impressing rolls 21 and 22 are the same, but sheet A enters between them from the left. A curved guide plate 60 is placed to the right of roll 22 and serves to maintain sheet A in contact with this roll over the right half of its periphery. On emerging from plate 60, the paper enters an accumulator assembly consisting of a bottom plate 61, a top plate 62, and a spring-pressed braking roll 63. The plates 61 and 62 are fixed in any convenient manner to the frame 20 of the machine, and the top and bottom surfaces, respectively, are parallel and spaced apart by a suitable distance to produce a slight drag on the paper passing between them. Roll 63 may be supported on a lever 64 which is mounted on a fulcrum 65 and restrained by a spring 66. Above, and to the left of this accumulator assembly is mounted a hollow roll 67 which is constructed so that a heated liquid may be circulated through it. This roll is mounted in fixed bearings on frame 20, and may be suitably driven to aid in the travel of the paper. Above roll 67 is mounted an endless belt 68, travelling around idler rolls 69, 70, 71 and 72, the latter two of which are disposed so as to cause the belt to pass around the upper half of roll 67. The adhesive spreader, consisting of reservoir 27, pick-up roller 28, and transfer roller 29, is mounted alongside of roll 67 in such a position as to apply adhesive to sheet A just before the sheet enters between roll 67 and belt 68. Sheet B is fed over a guide roll 73 so as to enter between belt 68 and roll 67, along with sheet A, in the region of roll 71. The two sheets are bonded together by the pressure of belt 68 as they pass around the upper half of roll 67, and the heat from the latter simultaneously dries the adhesive.
On leaving roll 67, the bonded sheets pass around a guide roll 74 and then between belt 35 and roll 34 and through the accumulator assembly consisting of plates 39, 40 and 41, and roll 42.
This machine is adapted to produce a modified form of paper by a modification of the method previously described. One sheet is first impressed with zigzag rows of corrugations, and then pleated by longitudinal compression. The second sheet is then bonded to the pleated sheet, and the bonded sheets are further'compressedtlongitudinally so as to produce pleats or straight'corrugations in the second sheet, and to bring the pleatsoftthe first closer together. The machine shown in Fig.v 10 can be used for making paper of the first type by raising roll 63 out of contact with sheet A, so that the sheet undergoes no longitudinal compression before bonding.
The modified form of paper is illustrated in Fig. 11 at the stage before its final compression. Sheet B has been bonded to sheet A along the regions of the fold lines 53 of the trough strips. After the final compression, this paper, illustrated in Fig. 12, appears very similar to that shown in Fig. 6 except that the pitch p of the pleats or straight corrugations is less, due tothe fact that the original pitch of the impressed corrugations of sheet A has been reduced before sheet B was applied, and the difference in height of the peaks ofthe: two sheets. is greater. This form of paper can be stretched only to the extent illustrated in Fig. 11, not to the point wherethe peak strips of the initially impressed zigzag corrugations of sheet A become flat. This form of paper thus retains somewhat greater crush resistance, when stretched to its fullest extent, than the form first described.
In either form of machine, the pressure of roll 42 determines the reduction in pitch of the combined sheets during the final compressing stage and, consequently, the degree to which the finished paper can be stretched in the longitudinal direction. This pressure can be varied in any suitable manner, for example, by varying the tension of spring 45, so as to produce paper with various degrees of extensibility.
These papers are flexible, as well as extensible in the longitudinal direction, and can be readily wrapped around tubular or irregularly shaped articles without losing their crush-resistant and cushioning properties. The papers are thus highly suitable for packing fragile objects. As sheet B serves primarily to limit the extension of sheet A, which provides the crush resistance of the finished paper, sheet B can be made of relatively light stock as compared to sheet A. A paper with a high degree of crush resistance can thus be economically produced. Both sides of the finished paper exhibit a regular wavy pleated formation which is pleasing to the eye, and the paper is thus decorative as well as highly useful as a wrapper.
What is claimed is:
1. A packing paper comprising a first layer of paper, formed with regular zigzag rows of corrugations of uniform height having peak and trough strips, and also with straight peak and trough folds disposed medially along the peak and trough strips, respectively, and a second layer of paper, bonded to the first along said trough strips and folded about said trough folds, said second layer having zigzag rows of corrugations aligned with the rows of the first sheet and peak portions intermediate said trough strips formed with peak folds of less height than the peak folds of the second strip, all the layers being extensible in a direction perpendicular to said rows, and the second layer being of shorter extended length than the first layer.
2. A packing paper comprising a first layer of paper, formed with regular zigzag rows of corrugations of uniform height having peak and trough strips, and also with straight peak and trough folds disposed medially along the peak and trough strips, and a second sheet of paper bonded to the first on substantially straight paths along said trough folds, said second sheet having zigzag rows of corrugations aligned with the rows of the first sheet with peak portions intermediate said trough folds formed with peak folds of less height than said peak folds, all the layers being extensible in a direction perpendicular to said rows, and the second layer being of shorter extended length than the first layer.
3. A packing paper comprising a first layer of paper formed with regularly spaced zigzag rows of corrugations of uniform height having alternating peaks and troughs, and a second layer of paper bonded to said first layer along the troughs thereof, said second layer having zigzag rows of corrugations aligned with the rows of the first sheet with portions intermediate said troughs formed into peaks of less height than those of the first layer, both layers being extensible in a direction perpendicular to said rows and .the second layer being of shorter extended length than the first.
4. A packing paper comprising a first layer of paper, formed with regularly spaced zigzag rows of corrugations of uniform height having peak and trough strips, and also with straight peak and trough folds disposed medially along the peak and trough strips, respectively,
and a second layer of paper bonded to the first along said trough strips and foldel about said trough folds, said second layer having zigzag rows of corrugations aligned with the rows of the first sheet with peak rows of less height than the peak folds of the first layer, and also having peak folds substantially aligned with the peak folds of the first layer, both layers being extensible in a direction perpendicular to said rows and the second layer being of shorter extended length than the first.
5. A packing paper comprising a first layer of paper, formed with regularly spaced zigzag rows of corrugations of uniform height having peak and trough strips, and also 25 with straight peak trough folds disposed medially along the peak and trough strips, respectively, and a second layer of paper bonded to the first on substantially straight paths along said trough folds, said second sheet having zigzag rows of corrugations with peak rows of less height than the peak folds of the first layer, and also having peak folds substantially aligned with the peak folds of the first layer, both layers being extensible in a direction perpendicular to said rows and the second layer being of shorter extended length than the first.
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