WO1985003029A1

WO1985003029A1 - Rolled paper embossing dispenser

Info

Publication number: WO1985003029A1
Application number: PCT/US1985/000029
Authority: WO
Inventors: Clarence H. Schatz
Original assignee: Scott Paper Company
Priority date: 1984-01-16
Filing date: 1985-01-10
Publication date: 1985-07-18
Also published as: CA1229326A; MX161192A; JPS61501084A; ES291900Y; IT8567037A0; AU3882485A; IT1182361B; EP0167622A4; IT8567037A1; AU586814B2; EP0167622A1; ES291900U; ES548927A0; BR8504140A; ES8609033A1

Abstract

A roll paper dispensing cabinet having means for rotatably supporting a roll of paper and a pair of rotatable embossing rolls providing a nip through which the paper is directed prior to exiting the cabinet. The embossing rolls, at least one of which includes a plurality of knuckles, cooperate to mechanically stress the paper beyond its elastic limit in spaced-apart regions over substantially the entire surface of the paper to reduce the cross-machine direction wet tensile strength of the paper by 25% and to increase the bulk of the paper more than 60% to thereby provide a dispensed sheet having enhanced softnesss, flexibility and absorbency.

Description

ROLLED PAPER EMBOSSI NG DI SPENSER TECHNICAL FIELD This invention relates generally to a cabinet for dispensing rolled sanitary paper products , and more particularly , to a dispensing cabinet in which a roll of sanitary paper is softened as it is dispensed .

BACKGROUND ART Rolled sanitary paper products such as paper toweling and toilet tissue are commonly dispensed from cabinets in public washrooms. When economy is a primary consideration , a relatively smooth , flat paper is wound very tightly into a roll to maximize the length of paper for a given diameter of the roll. By maximizing the length of paper on the roll , the roll generally lasts longer which increases the time between roll replacement in the cabinet. The cabinet may also contain a second roll of paper that automatically begins feeding as the first roll expires which further increases the time between servicing of the cabinet. When economy is a primary consideration , it is also common to use lower graded , such as unbleached or low brightness , papers in these cabinets . The economy rolled paper product can generally be characterized as dense, stiff and having limited absorbency when compared to higher quality sanitary paper products .

When economy is not a primary consideration and it is desired to provide a higher quality rolled sanitary paper product in the dispensing cabinet, the usual approach has been to pre-treat, usually by embossing , the paper sheet prior to winding it on a roll . As used in this specification , the term embossing means raising the surface of the paper sheet into bosses or protuberances in such a manner that the length of the embossed sheet is substantially the same as the length of the sheet prior to embossing . Depending on the method of embossing , the length of the embossed sheet can be as much as 5% shorter than the length of the sheet prior to embossing , but more typically is in the range of 0-3% shorter than the length of the sheet prior to embossing . One shortcoming of dispensing embossed paper after it has been wound on a roll is that the winding operation flattens the bosses formed in the paper with the result that the dispensed paper has less bulk, softness and absorbency than the embossed paper had prior to being wound on the roll . On the other hand , if the pre-treated , embossed paper is wound loosely on the - roll in order to retain the bulk and softness from the embossing process, considerably less footage is wound on the roll and the dispensing cabinet requires much more frequent servicing . Another shortcoming of dispensing an embossed paper, particularly in the case of paper toweling , is the fact that in most rolled towel cabinets, the paper toweling is normally dispensed by compressively passing the toweling through a nip formed by two feed rolls . U .S . Patent 1 ,224,224, issued to Robert M. Shelley, is representative of such a dispensing cabinet. This compressing of the paper also tends to reduce the effects of the prior embossing.

One approach for improving the quality of rolled sanitary products dispensed from a cabinet is disclosed in U .S . Patent

3 ,935 ,802 - Perrin , et al . Perrin , et al treat the paper web in the dispensing cabinet by passing it between a drive roil and a driven roll each having formed on the periphery thereof a multiplicity of generally axially extending and circumferential ly adjacent teeth (column 5 , lines 57-63) . At column 6 , lines 42-48 , Perrin , et al state that as the plain or smooth paper toweling web is drawn through and variously compressively abutted between the drive roll teeth and the driven roll teeth , and over the various crests of these teeth , the plain paper toweling web is foldably deformed into a crimp'ed or serrated paper toweling web . Further , at column 6 , lines 50-64, Perrin , et al state that the treatment of the paper toweling by the rolls should be controlled so that the paper web does not undergo any appreciable permanent thickness deformation or permanent compression . At column 8 , lines 6-11 , Perrin , et al state that, the crimped web has improved qualities without any sacrifice of moisture strength . One disadvantage of Perrin , et al is that the effective length of the dispensed sheet is inversely related to the gain in bulk achieved by crimping. Another disadvantage of Perrin , et al is based on the well established fact that for sanitary papers softness and strength are inversely related and , therefore, any bulking process that maintains the moisture strength of the dispensed sheet results in only slight improvement in sheet softness .

It is an object of this invention to provide means for embossing relatively flat and dense rolled paper as it is being dispensed from a cabinet so that the dispensed paper exhibits the softness , flexibility , and absorbency of higher quality paper while simultaneously achieving the economy heretofore associated only with the dispensing of low quality paper.

It is another object of this invention to reduce the tensile strength of rolled paper product In a cabinet by passing the paper through a set of embossing rolls which stresses the paper beyond its elastic limit in spaced-apart regions.

It is yet another object of this invention to emboss a rolled paper product in a dispensing cabinet so that the thickness of the embossed paper is from 80% to 600% greater than the original thickness of the paper.

Another object of this invention is to emboss sanitary paper in a dispensing cabinet and dispense the embossed sheet to the user without subjecting the embossed sheet to any subsequent compressive force which might reduce the bulk , softness and absorbency provided in the embossing step .

It is yet another object of this invention to increase the bulk of sanitary paper as it is dispensed from a cabinet without substantially decreasing the length of the dispensed paper .

DISCLOSURE OF THE I NVENTION

A rolled paper dispensing cabinet in accordance with this invention includes means for rotatably supporting a rol l of paper • within the cabinet. The dispensing cabinet includes a pair of rotatable embossing rolls providing a nip through which the paper is directed prior to exiting the cabinet. At least one of the embossing rolls has a plurality of knuckle projections, and the embossing rolls cooperate to mechanically stress the paper beyond its elastic limit in spaced apart regions over substantially the entire surface of the paper to reduce the cross machine direction tensile strength of the paper by at least 25% and to increase the bulk of the paper by at least 60% thereby providing a dispensed paper web having enhanced softness , flexibility and absorbency . This invention is particularly suited to dispense dense paper toweling that is tightly wound on a roll . The dense structure of this toweling maximizes the amount of paper that can be stored in roll form within the limited space available in the cabinet. The embossing rolls can increase the bulk of the roll toweling by as much as 500%, and probably as much as 600%, and can also reduce the wet and dry tensile strength by more than 50%. This higher bulk, and lower tensile toweling that is dispensed has the flexibility , softness and absorbency normally associated with high quality paper toweling while retaining all of the economic benefits normally associated with dispensing lower quality paper.

It is within the scope of this invention to employ various arrangements of embossing rolls to mechanically work the paper as it is directed out of the cabinet. For example, one of the embossing rolls can have a plurality of rigid knuckle projections while the other embossing roll has a smooth surface made, for example, out of an elastomer . In a preferred embodiment of the invention , both embossing rolls have opposed cooperating discrete knuckle projections having closely positioned side margins that engage and mechanically work the paper beyond the elastic limit to form thin , diaphanous regions therein , which , in some cases , can actually be in the form of tears or cuts. BRIEF DESCRIPTION OF THE DRAWI NGS While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention , the objects and advantages of this_^ invention can be more readily ascertained from the following description of a preferred embodiment when read in conjunction with the accompanying drawings in which :

Fig . 1 is a side elevational view illustrating a rolled paper dispensing cabinet of this invention ; Fig . 2 is a fragmentary front elevational view of one type of embossing rolls which can be employed in the dispensing cabinet of this invention ; Fig . 3 is a sectional view along line 3-3 of Fig . 2 illustrating a floating ring system for ensuring that the embossed paper is stripped from the embossing rolls as it exits the embossing nip;

Fig . 4 is an enlarged sectional view through the nip of one type of embossing rolls , with the web removed , showing one manner in which the projections of the opposed embossing rolls can be arranged to cooperate with each other, the projections of the top roll being shown in section ; and Fig . 5 is a cross-sectional view of an alternate embodiment of embossing rolls.

BEST MODE FOR CARRY ING OUT THE INVENTION Referring to Fig . 1 , a dispensing cabinet 10 of this invention is schematically illustrated as including a pair of idler rolls 12 , 14, for guiding paper toweling 16 from a roll 18 through a nip 20 formed by a pair of embossing rolls 22 and 24. Rotary motion applied to a crank 26 is applied through conventional gearing means (not shown) which cause rotation of the embossing rolls 22 and 24 in opposite directions as indicated by arrows in Fig . 1 . It should be understood that the present invention can be practiced in many different forms , and that the dispensing cabinet 10 depicted here is shown solely for the purpose of exemplification. For example, this invention can be used to simultaneously soften and dispense toilet tissue.

Referring now to Fig . 2 , there is shown an embossing arrangement in which feed roll 22 includes a plurality of discrete knuckle projections 28 which cooperate with respective discrete knuckle projections 34 on embossing roll 24. The discrete knuckle projections 28 of embosssing roll 22 are aligned in axially spaced-apart, circumferential rows , as indicated by lines 30a-30d . The discrete knuckle projections 28 in each row 30a-30d are also circumferential ly offset from the projections in an adjacent row. As a result of this arrangement, the knuckle projections 28 in adjacent rows also align along helical paths as represented by lines 32a and 32b. The discrete knuckle projections 34 of embossing roll 24 are arranged in a pattern of circumferential rows as indicated by lines 36a-36c that are identical to the pattern of knuckle projections 28 on the roll 24, but are axially offset therefrom . The embossing rolls 22 and 24 are mounted in the dispensing cabinet 10 so that the knuckle projections 28 of roll 22 extend into the spaces between the knuckle projections 34 of embossing roll 24. The distance that the projections 28 on roll 22 overlap with the projections 34 on roll 24 will be referred to as penetration in -subsequent sections of this specification . A preferred relationship of the knuckle projections 28 on embossing roll 22 to the knuckle projections 34 on embossing roll 24 in the nip 20 is illustrated in Fig . 4. In order to simplify the illustration , the knuckle projections 28 and 34 are shown as existing in planes rather than on cylindrical surfaces , and the knuckle projections 28 on roll 22 are illustrated in section . As shown in Fig . 4, each projection 34 on embossing roll 24 is spaced closely to a projection 28 on the opposed embossing roll 22 to extensively stress or work the paper sheet 16 beyond its elastic limit as the sheet is being directed through the nip 20 of the embossing rolls 22 and 24. The side edge 46 of knuckle projection 28 is adjacent to the side edge 48 of knuckle projection 34 and acts upon the paper web 16 to form thin , diaphanous regions which , under conditions of deep penetration , actually can be cuts or tears. In one constructed embodiment of the invention , each of the embossing rolls 22 and 24 has a pitch diameter of approximately 1 .0 inch ( 25.4 mm) and , as shown in Fig . 4, both rolls 22 ,24 have hexagonal knuckle projections 28 ,34 having an axial dimension , or width , W , of approximately 0.034 inches (0.86 mm) and a circumfer- ential dimension , or length , L, of approximately 0.082 inches (2.08 mm) . The center-to-center axial distance, X , between the circumferentially offset projections 28 ,34 in adjacent rows is approximately 0.081 inches ( 2.06 mm) , and the center-to-center circumferential difference , M , between adjacent projections 28 ,34 in each row is approximately 0.162 inches (4.11 mm) . The height of the knuckle projections 28 , 34 are approximately 0.044 inches (1 .12 mm) and the embossing rolls 22 ,24 can be mounted so that the knuckle projections 28 , of row 22 penetrates or overlap with the knuckle projections 34 of roll 24 by as much as 0.040 inches ( 1 .02 mm) .

The side walls 46 and 48 of the knuckle projections 28 , 34 are inclined outwardly in a downward direction from the crest of the projections. The angle of inclination^' of the circumferentially oriented sidewalls 46 , 48 is about 2 degrees , while the angle of inclination of the diagonally oriented side walls 50 and 52 is about 10 degrees . The various dimensions set forth above are those measured at the crest of the knuckle projections 28, 34.

Table 1 indicates both the bulk and cross-machine direction dry and wet tensile (CMDDT , CMDWT) strength of a paper towel 16, prior to embossing it, and the increase in bulk and decrease in cross-machine direction tensile strength experienced by the paper as a result of being subjected to embossing rolls 22 and 24 as described in detail in the preceding two paragraphs . In table 1 , the amount of overlap of the knuckle projections 28 ,34 in the nip 20 under low penetration conditions was 0.020 inches (0.51 mm) , under medium penetration conditions was 0.026 inches (0.66 mm) , and under high penetration conditions was 0.032 inches (0.81 mm) .

The cross-machine direction tensile strength data in Table 1 was determined in accordance with TAPPI standard T 494 OS 70 , with the one exception that only a two inch (50.8 mm) span was employed , and the specimen was strained at two inches (50.8 mm) per minute.

The bulk data in Table 1 was obtained by employing a Federal bulker, having an upper platen measuring 1 .128 inches (28.65 mm) in diameter, and a lower platen having a diameter larger than that of the upper platen . A total dead load of 235 grams (plus or minus 3 grams) was gently applied to the test specimen and a reading was taken five seconds later. The test specimen consisted of a stack of 12 sheets of dry paper toweling and two separate readings were taken at random locations. The two readings then were totaled to provide a bulk number representative of a 24 sheet specimen , and this is the bulk number reported in Table 1 . The unit of the reading is 0.001 inch (0.025 mm) , and therefore, the reported bulk reading is a thousand times greater than the actual thickness of a 24 ply specimen . TABLE 1

Bulk CMDWT (Ounces per 1 .0 inch strip)

(28.35 g per

25.4 mm)

No Embossing 131 12.1

Low Penetration 274 8.7 (0.020 inch) (0.51 mm)

Medium Penetration 388 6.7

(0.026 inch) (0.66 mm)

High Penetration 468 5.6 (0.032 inch) (0.81 mm)

As shown in Table 1 , the embossing rolls 22 ,24 increased the bulk of the paper by about 100% under low penetration conditions to well over 200% under high penetration conditions. Similarly, under low penetration conditions, the cross machine direction wet tensile of the paper is reduced by about 28% under low penetration conditions and by over 50% under high penetration conditions. Because of the higher bulk and the improved softness accompanying the decrease of wet tensile, most users would prefer the paper towel that was formed with the high penetration embossing rolls 22 ,24.

The data in Table 1 shows that for paper suitable for use as paper toweling , which typically has a basis weight in the range of about 20 to 40 pounds per 2 ,880 square feet (0.034 to 0.068 kilograms per square meter) relatively low penetration embossing will result in reducing the cross machine direction tensile by at least 25% while increasing the bulk by at least about 80%. Although the data of Table 1 illustrates the improve-ments for paper toweling , it will be apparent to those skilled in the art that paper suitable for use as toilet tissue, typically having a basis weight in the range of about 10 to 120 pounds per 2 ,880 square feet (0.017 to 0.034 kilograms per square meter) can also be improved using the embossing cabinet and method of this invention . Embossing of the low penetration lights, tissue weight paper will resuts in about the same 25% decrease of dry tensile strength of the web, however, the measured bulk of the embossed tissues will tend to be less , about 60% than for the towel weights exemplified in Table 1 . The lower increase in bulk of the lighter weight tissue is explained by the fact that although a lighter weight web and a heavier weight web undergo the same embossing step , during the bulk measuring process , the lighter weight embossed web will collapse more than the heavier weight embossed web in response to the load applied during the test and will , therefore, indicate less measured bulk, even though substantially the same bulk was improessed into the sheet. One problem that might be encountered in roll paper dispensing cabinets that employ embossing rolls 22 ,24 is that the paper may adhere to and wrap around one of the embossing rolls 22 ,24 instead of separating, from the embossing rolls 22 ,24 and exiting through the dispensing orifice 54 of the cabinet 10. One arrangement for preventing the paper 16 from wrapping one of the embossing rolls 22 ,24 is illustrated in Figs. 2 and 3. A plurality of rings 40 are located in grooves 56 in embossing roll 22. The rings 40 are axially offset relative to a second set of rings 42 located in grooves 58 in embossing roll 24, The rings 40 and 42 have an diameter that is larger than the diameter of the respective rolls 22 ,24. These rings 40 ,42 are slightly narrower than the width of the grooves 56 ,58 in which they are received so that they are free to float therein . Most preferably the grooves 56 ,58 in which the rings 40 ,42 are intended to be retained are actually machined inwardly of the working surface ( i .e. the surface toward which the projections of the opposing roll approach) a distance greater than the radial thickness of the rings 40 ,42 to thereby form annular recesses 60 ,62 , best shown in Fig . 3. In a typical arrangement, the annular recesses 60,62 have a depth of approximately 0.030-0.040 inches (0.76-1 .02 mm) , and the radial thickness of the rings 40 ,42 is slighty smaller. As a result of this arrangement, at the nip 20 , the surface of the projections 28 ,34 retain the rings 40 ,42 in the annular recesses 60 ,62 of grooves 56 , 58 thereby forcing the rings 40 ,42 into the position shown in Fig . 3. Specifically , the downstream portion of the rings 40, 42 (the portion of the rings 40 ,42 located beyond the nip 20 of the embossing rolls 22 ,24 in the direction of rotation of the embossing rolls 22 ,24) extend outwardly beyond the crest of the embossing roll projections , 28 engage the embossed sheet 16 and direct it off of the projections 28.

Although the embodiments depicted in Figs. 1 -4 show both embossing rolls 22 ,24 having knuckle projections 28 ,34 that cooperate to emboss the paper sheet 16 , it will be understood by those skilled in the art that other roll configurations can also be employed to accomplish embossing .

For example, as shown in Fig . 5 , embossing can be accomplished by means of an embossing roll 22 having a plurality of knuckle projections 28 cooperating with a roll 24 that has a smooth , ^' somewhat resilient surface.

Examples of materials out of which roil 24 can be constructed or covered are natural rubber, neophene, urethane and neoprene foam elastomers. Also, although the illustrated embossing rolls 22 ,24 employ discrete knuckle projections , it will be appreciated by those skilled in the art that continuous raised knuckles in the shape of lines or ridges can also be employed .

In the preferred embodiment, the embossing pattern covers the entire area of the dispensed sheet. However, in some cases , it may be desirable to cover substantially the entire surface of the sheet while leaving small areas of the sheet unembossed . For example , the edge of the sheet might remain unembossed , or if the embossing rolls 22 ,24 have grooves 56 ,58 as part of an arrangement to prevent wrap-up of the paper around the embossing rolls 22 ,24, the dispensed sheet may have unembossed lines corresponding to the grooves 56 ,58. The embossed sheet might also have narrow unembossed strips extending in the cross direction from one edge of the sheet to the other edge of the sheet. It may also be desirable for aesthetic purposes to have unembossed regions which form a pattern in the sheet.

I n the most preferred embodiment of this invention , the embossed sheet is not subjected to any substantial compression between the point that it leaves the embossing roils 22 ,24 and the exit orifice 54 of the dispensing cabinet 10 so that substantially all of the benefits obtained by mechanically treating the paper sheet 16 is passed on to the ultimate user of the embossed sheet.

While the present invention has been described with reference to a specific embodiment thereof, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention in its broader aspects . For example, although a crank 26 has been shown as causing rotation of the embossing rolls 22 ,24, it will be appreciated by those skilled in the art that other means such as a lever could also be used to cause rotation of embossing rolls 22 ,24.

Claims

What is claimed as new and desired to be secured by Letters Patent of the U . S. is:

1 . A rolled paper dispensing cabinet comprising:

^ (a) means for rotatably supporting a roll of paper in the cabinet;

(b) a pair of rotatable embossing rolls providing a nip through which the paper is directed prior to exiting the cabinet; at least one of the embossing rolls having a plurality of knuckles, the embossing rolls cooperating to mechanically stress the paper beyond its elastic limit in spaced-apart regions over substantially the entire surface of said paper to reduce the cross-machine direction tensile strength of the paper over 25% and to increase the bulk of the paper over 80% to thereby provide a dispensed web having enhanced softness , flexibility and absorbency; and

(c) means for rotating one of the embossing rolls to thereby feed the paper through the nip of the embossing rolls.

2. A roll paper dispensing cabinet as recited in claim 1 wherein the embossed paper is not subjected to any substantial compressive force prior to exiting the cabinet whereby substantially all of the benefits of the embossing is available to a user of the embossed sheet.

3. A roll paper dispensing cabinet as recited in claim 1 wherein the paper has a basis weight between 20 and 40 pounds per 2 ,880 square feet.

4. A roll paper dispensing cabinet as recited in claim 1 wherein the paper has a basis weight between 10 and 20 pounds per 2 ,880 square feet and wherein the embossing rolls increase the bulk of the paper by more than 60%.

5. A roll paper dispensing cabinet as recited in claim 1 wherein both of the embossing rolls have opposed , cooperating knuckle projections for mechanically stressing the paper.

6. A roll paper dispensing cabinet as recited in claim 1 wherein one of the embossing rolls has a smooth resilient surface.

7. The roll paper dispensing cabinet of claim 1 characterized in that the embossing rolls have a pitch diameter of about one inch (25.4 mm) .

8. The roll paper dispensing cabinet of claim 1 characterized in that the knuckle projections of at least one of the embossing rolls are discrete, individual projections spaced apart both axially and circumferentially on said roll .

9. The roll paper dispensing cabinet of claim 5 characterized in that the opposed cooperating knuckle projections include closely adjacent side margins for engaging and mechanically working the paper to form diaphanous regions therein .

10. The roll paper dispensing cabinet of claim 9 characterized in that the opposed cooperating knuckle projections stress the paper beyond its elastic limit to reduce the cross-machine direction wet tensile strength more than 40% and to increase the bulk over 200%.

1 1 . The roll paper dispensing cabinet of claim 9 characterized in that the opposed cooperating knuckle projections include a^' plurality of discrete, individual projections spaced apart both axially and circumferentially on the rolls.

12. A method of softening a rolled paper product as it is dispensed from a cabinet characterized by the steps of:

(a) rotatably supporting a roll of paper in the cabinet;

(b) then directing paper from the roll through a nip formed by a pair of embossing rolls to mechanically stress the paper beyond its elastic limit in spaced-apart regions over substantially the entire surface of the paper so that the cross-machine direction tensile strength of the paper is reduced by at least 25% and the bulk of the paper is increasd by at least 80%; and (c) then , without subjecting the embossed sheet to any substantial compressive forces , directing the embossed sheet through an exit orifice of the cabinet.

13. The method of claim 11 wherein the paper has a basis weight of between 10 and 20 pounds per 2 ,880 square feet and wherein the embossing step increases the bulk of the paper by at least 60%.

14. The method of Claim 12 wherein the embossing rolls stress the paper so that the cross-machine direction tensile strength of the paper is reduced by at least 40% and the bulk of the paper is increased by at least 400% .

15. The softened paper made in accordance with the method of Claim 12.

16. The softened paper made in accordance with the method of Claim 13.

17. The softened paper made in accordance with the method of Claim 14.