CENTER-PULL NAPKIN DISPENSER WITH CONTROLLED WRINKLING

Center-pull napkin dispensers and methods of supplying napkins for the same are disclosed. A center-pull napkin dispenser may comprise a body for supporting at least one roll of perforated paper napkins and a nozzle comprising a nozzle opening configured for dispensing napkins therethrough. The nozzle opening defines a nozzle cross-sectional area (AN) and the roll of paper napkins defines a cross-sectional material mass (X). The nozzle cross-sectional area divided by the cross-sectional material mass and multiplied by a constant C=10,000, is about (AN/X)*C≧0.85. A method of supplying napkins for a center-pull napkin dispenser may comprise the steps of providing a center-pull napkin dispenser comprising a nozzle opening that defines a nozzle cross-sectional area (AN); providing a roll of paper napkins such that the nozzle cross-sectional area divided by the napkin cross-sectional material mass (X) multiplied by the constant, is about (AN/X)*C≧0.85. An objective wrinkle index is also disclosed.

DETAILED DESCRIPTION

Structural Features of Various Embodiments

FIG. 1shows a center-pull napkin dispenser10according to various embodiments. A center-pull napkin dispenser10may comprise a body11configured for supporting at least one roll of perforated paper napkins20. A center pull napkin dispenser10comprises at least one nozzle12configured for dispensing paper napkins25. In various embodiments, the center-pull napkin dispenser10is configured to control the amount of wrinkling of napkins dispensed by the center-pull napkin dispenser, as represented by a wrinkle index (W). Some of the features of various embodiments of the center-pull napkin dispenser10will be discussed in detail below.

As shown inFIG. 1, the center-pull napkin dispenser comprises a body11configured for supporting at least one roll of perforated paper napkins20. In various embodiments, the body11may be generally circular or elliptical in cross-section. In other embodiments, the body11may have a cross-section that is generally square, rectangular, or alternatively shaped.

In various embodiments, the body11may be made of plastic, metal or some other suitable material. In various embodiments, the body11may be configured to be mounted on a wall, ceiling, or the like. In other embodiments, the body11may be configured to rest on a table, counter, shelf or the like. In some embodiments, the body11may be configured such that the user may choose whether to mount the center-pull napkin dispenser10or set the center-pull napkin dispenser10on a table, counter, or the like.

In various embodiments, the body11may be configured to support one roll of paper napkins20. In other embodiments, the body11may be configured to support two or more rolls of paper napkins20. In various embodiments, the body11may comprise a selectively removable or hingedly removable door14that may be opened to place at least one roll of napkins20into the body11. In other embodiments, a different mechanism may be used to position a roll of napkins20into the body11, such as an opening at the top of the body. In still other embodiments, the body11may support at least one roll of napkins20, but the napkins may not be placed inside the body11.

In various embodiments, the body11may further comprise a fullness gauge15or window that may indicate how many napkins have been dispensed, how many napkins are still present on the roll of napkins20, the percentage of the roll of napkins that has been dispensed, or may simply indicate when the supply of napkins supported by the body falls below a pre-determined threshold. The fullness gauge15may count the number of napkins dispensed, may measure the volume of napkins dispensed, may measure the volume or mass of the napkins remaining on the roll, or use some other suitable method to indicate when the supply of napkins supported by the body is running low.

It should be understood that a variety of variations of the body11are within the scope of the present invention.

Remaining withFIG. 1, and as noted above, a center-pull napkin dispenser10comprises a nozzle12, and the nozzle12is operatively connected to the body11. In various embodiments, the nozzle12is configured for dispensing napkins25from various locations on or adjacent to the body, such as on or in the bottom surface of the body. For example, the nozzle12could be on the top surface of the body11or in a side thereof, and could also be positioned at a distance from the body. In various embodiments, the nozzle12may be made of plastic, or metal, or some other suitable material.

FIGS. 2A-2Cillustrate a variety of nozzles according to various embodiments. In various embodiments, the nozzle12may be generally circular or elliptical in cross-section. In some embodiments, the nozzle12may have a cross-section that is generally rectangular, rectangular with rounded corners, triangular, or alternately shaped.

The nozzle12defines at least one opening121disposed therein configured for dispensing napkins25from the at least one roll of napkins20supported by the body11. In various embodiments, the nozzle opening121may be generally circular, triangular, or slot-shaped, such as generally elliptical, rectangular, or rectangular with rounded corners shaped. In other embodiments, the nozzle opening121may be “dog bone”-shaped or slot shaped with rounded ends wherein the nozzle opening is wider at the ends than in the middle of the slot. The nozzle opening121may have a variety of other shapes as well without departing from the scope of the present invention. In various embodiments, the nozzle opening121may further comprise projecting restrictions122. The projecting restrictions122may have a variety of shapes in various embodiments. It should be appreciated that a wide variety of nozzle shapes are commonly known and understood in the art and may be used in various embodiments of the present invention.

The nozzle opening121defines a nozzle area (AN). The nozzle opening121defines an effective diameter (D) that is the diameter of a circle having the same area as the nozzle opening121. In various embodiments, the nozzle opening121may have an effective diameter (D) of about 0.40 inches, 0.53 inches, 0.63 inches, or 0.77 inches. In some embodiments, the nozzle opening121may have an effective diameter (D) in the range of 0.3 to one inch. As is discussed in detail below, the acceptable range of effective nozzle opening diameters (D) is determined by a lower limit wherein the napkin25separates from the web of paper napkins20before the napkin has been fully dispensed by the center-pull napkin dispenser10and an upper limit wherein the napkin does not separate from the roll of napkins when the napkin is dispensed by the center-pull napkin dispenser (i.e. “roping”).

In various embodiments, the shape or size of the nozzle opening121are not changeable. In other embodiments, the nozzle opening121may be adjustable in shape and/or nozzle cross-sectional area (AN). In some embodiments, a spring-loaded bar that partially impedes the nozzle opening121may be used, allowing the center-pull dispenser10to accommodate rolls of napkins20of various basis weights. In other embodiments, a nozzle12may be removed and replaced with a nozzle12of the same or different nozzle opening shape and/or nozzle cross-sectional area (AN). In other embodiments, the nozzle12may have more than one nozzle opening121and a user may select which nozzle opening121to dispense napkin25through.

In various embodiments, the nozzle121may further comprise a blade or cutting or ripping device (not shown) configured for helping separate an individual napkin25from the roll of napkins20as the napkin25is dispensed. In other embodiments, the roll of paper napkins20may be sufficiently perforated that a blade or cutting or ripping device may not be needed to separate an individual napkin25from the roll of napkins20as the napkin25is dispensed.

A variety of paper webs are commonly known and understood in the art that may be used to make various embodiments of a napkin25. For example, in various embodiments, napkin25may be made from a single ply web. In other embodiments, napkin25may be made from a double ply web, or even more plies. In various embodiments, napkin25may be embossed. In other embodiments, napkin25may not be embossed. In some embodiments, the napkin25may be a beverage or cocktail napkin. The paper web from which napkin25is made may define a web width (ww). In various embodiments, the napkin25may be about six and a half inches (ww=6.5″) in width. In other embodiments, for example when napkin25is a beverage napkin, the napkin may be about four and a half to five and a quarter inches wide (ww=4.5-5.25″). For example, in certain embodiments, the napkin25may have a width of about five to eight inches (ww=5-8″) or about four and a half inches to eight inches (ww=4.5-8″). In other embodiments, the napkin25may be four to six and a half inches (ww=4-6.5″) in width. In still other embodiments, the napkin25may be greater than six and a half inches (ww>6.5″) in width. For example, in certain embodiments, the napkin25may be six and a half to nine inches (ww=6.5-9″) wide or nine inches to twelve inches (ww=9-12″) wide. The length of a napkin (l) is determined by the spacing of perforations along the length of the paper web. In various embodiments, the length of napkin25may be about eight and a half inches (l=8.5″). For example, in certain embodiments, the napkin25may have a length of six to ten inches (l=6-10″). In other certain embodiments, the napkin25may have a length of four and a half to ten inches (l=4.5-10″). In other embodiments, the napkin25may be five to eight and a half inches (l=5-8.5″) long. In some embodiments, for example when the napkin25is a beverage napkin, the length of the napkin may be about four and a half to five and a quarter inches long (l=4.5-5.25″). In yet other embodiments the napkin25may be longer than eight and a half inches (l>8.5″) in length. In certain embodiments, the napkin25may be eight and a half to twelve inches (l=8.5-12″) or twelve to fifteen inches (l=12-15″) in length.

In various embodiments, the napkin25is pulled through the nozzle opening121at an angle due to its unwinding from the roll of perforated napkins20. Therefore, the effective width (we) of the napkin from the perspective of the nozzle may be greater than the web width, or we≧ww. The effective width (we) may vary between various embodiments depending on various factors that may comprise: the relative positioning of the nozzle12to the roll of paper napkins20, what portion of the trailing napkin is pulled through when a napkin25is dispensed, and/or the like. In various embodiments, there may also be a small variation in the effective width (we) depending on from where in the roll of napkins20the napkin25is pulled as a function of the open diameter at the center of the roll, at what point along the napkin the measurement is made, and/or the like. Finally the effective width (we) will vary slightly as a function of the instantaneous degree and direction of folding of the napkin as it is pulled through the nozzle12.

As noted above, the web width (ww) sets a lower bound for the effective width (we). In various embodiments the effective width (we) may be calculated as we=ww/cos φ, as shown inFIG. 3. In various embodiments, the angle φ is typically 30-50°. In certain embodiments, it is possible that φ<30° or φ>50°. In the calculations completed herein, the effective width (we) of the napkin as it passes through the nozzle opening121is approximated as we=ww/cos φ, wherein the angle φ=40°. It should be appreciated that a variety of other approximations of the effective width (we) may be used without departing from the scope of the invention.

The paper web from which napkin25is made may also define a web caliper or thickness (cw) and a basis weight (bw). An apparent density (da) of the web may be approximated as the basis weight divided by the web caliper or da=bw/cw. From this, a cross-sectional material mass (X) of the web may then be defined as the napkin width times the apparent density, or X=we*da. The applicant has discovered that the amount of wrinkling suffered by a paper napkin is related to the amount of paper that is pulled through a nozzle at any given time, and that the cross-sectional material mass (X) provides a valuable parameter for controlling the wrinkling of a paper napkin, although other measures of the cross-sectional material mass (X) or measures which capture the same or similar properties of napkin25may be employed based on the disclosure herein.

Wrinkle Index (W)

An objective measure of napkin wrinkling may be determined such that the level of wrinkling experienced by various napkins25may be compared. In various embodiments, a wrinkle index (W) for a napkin25may be determined by considering the number of wrinkles, the size of the wrinkles, the depth of the wrinkles, and/or other parameters.

FIGS. 4A-4Billustrate a front and side view of a projected area of an unwrinkled napkin21having the same length and width measurements as the effective length and width measurements of a corresponding projected area of a wrinkled napkin22illustrated inFIGS. 5A-5B. Due to the vertical variations caused by the wrinkles23, the wrinkled napkin22will have a larger surface area than the unwrinkled napkin21for the same projected area. In other words, a wrinkled surface with the same effective length and width dimensions as a smooth, unwrinkled surface will have a larger surface area than the unwrinkled surface. Thus, comparing the surface area of the unwrinkled napkin21to the wrinkled napkin22provides an objective measure of the degree of wrinkling experienced by wrinkled napkin22. Therefore, it is possible to define a wrinkle index (W) such that the wrinkle index is the surface area of the wrinkled napkin22(Aw) projected area minus the unwrinkled napkin21projected area (As) with that result divided by the surface area of the unwrinkled napkin21projected area (As), or expressed as W=[(Aw−As)/As]*100. Thus, in various embodiments, the wrinkle index (W) may be dimensionless. In other embodiments, the wrinkle index (W) may have various dimensions. Thus, it should be appreciated that, given the disclosure herein, a variety of measures of the wrinkling experienced by a napkin, paper product, or other sheet product could be used without departing from the scope of the present invention.

In various studies, the Applicant used a Taylor Hobson CLI 1000 scanning laser profilometer to determine the sample area (As) and the wrinkled napkin surface area (Aw). This instrument provides a non-contact, non-destructive technique to quantitatively measure surface topography. The data output by the CLI 1000 used in these studies were three dimensional surfaces. To gather the data, the napkin sample was placed on a glass slide and provided to the CLI 1000 for scanning. Due to the sensitivity of the CLI 1000, a low-pass Gaussian filter, as defined according to the ISO 11562 standard, with a cut-off wavelength of 3.5 mm was applied to the raw data to distinguish the wrinkling of the napkin from the fiber-level roughness and/or embossment of the napkin.

FIGS. 6A-6Cshow three wrinkled napkin samples and the measured wrinkle index for each sample. As can be seen fromFIG. 6A, a wrinkle index of W>2.5 indicates the napkin is very wrinkled, and, depending on the intended use, likely too wrinkled to be pleasing to a consumer.FIGS. 6B and 6Cshow that a wrinkle index of W<1.0 indicates a much less wrinkled napkin than a wrinkle index of W>2.5. For various applications, a consumer may find a napkin with a wrinkle index W<1.0 or W<0.5 to be acceptable and/or pleasing.

FIGS. 7A-7Fshow the measured wrinkle index (W) of various napkins25dispensed by various embodiments of a center-pull napkin dispenser10. These data points were collected by using an Instron universal testing machine to apply a pulling-down force from a roll defining a vertical axis resulting in a maximum cross-head speed of 40 inches/minute. The force was applied directly down (i.e., with a deviation of 0 degrees from vertical) from the leading tip of the napkin25protruding from the center-pull dispenser10.

FIGS. 7A-7Fshow how, in various embodiments, the wrinkle index (W) depends on the nozzle-paper ratio (R), wherein the nozzle-paper ratio is the nozzle cross-sectional area (AN) divided by the napkin cross-sectional material mass (X) or R=AN/X. The x-axes ofFIGS. 7A-7Fshow the dimensionless scaled nozzle-paper ratio (Rs), wherein the scaled nozzle-paper ratio is the nozzle-paper ratio multiplied by a constant (C); thus, Rs=C*R=(AN/X)*C. InFIGS. 7A-7F, the constant used is C=10,000. In other embodiments, different scaled nozzle-paper ratios may be defined that use various constants (C) and resulting in various units. In various other embodiments, a nozzle-paper ratio may be defined using the diameter (D) of a circle having the same area as the nozzle opening as a stand in for the nozzle cross-sectional area (AN) or some other suitable description of size of the nozzle opening121. Similarly, in other embodiments, the napkin cross-sectional area, napkin width, napkin volume, napkin density, or other parameter describing the amount of napkin25passing through the nozzle opening121at a given instant may be used in place of the napkin cross-sectional material mass (X). Thus, it should be appreciated that a variety of variations of the nozzle-paper ratio and the scaled nozzle-paper ratio disclosed herein may be defined without departing from the scope of the present invention.

FIGS. 7A-7Dshow the relationship between the wrinkle index (W) and the scaled nozzle-paper ratio (Rs) for a variety of napkins25with varying basis weight and caliper measurements.FIGS. 7D-7Fshow the relationship between the wrinkle index (W) and the scaled nozzle-paper ratio (Rs) for a variety of napkins25with varying bond areas, wherein the bond area describes the amount of perforation between two consecutive napkins on a roll of napkins. The bond area describes the percentage of the total width of a web remaining along a line of perforation separating two napkins after the perforations have been made across the web.

Table 1 provides the basis weight, caliper, and bond area for the napkins used in the trials in which the data used to produceFIGS. 7A-7Fwas collected. The width and length of all napkins used in these trials was six and a half inches (6.5″) and eight and a half inches (8.5″), respectively, and nozzle configured as inFIG. 2Awas used.

For the trials illustrated inFIGS. 7A-7F, the wrinkle index (W) tends to decrease with increasing scaled nozzle-paper ratio (Rs). Thus, in various embodiments, the wrinkling experienced by a napkin25being dispensed from a center-pull napkin dispenser10may be controlled by choosing an appropriate scaled nozzle-paper ratio (Rs) for the intended application.

Surprisingly, the wrinkle index (W) does not have a linear relationship with the scaled nozzle-paper ratio (Rs) and decreases drastically with increasing scaled nozzle-paper ratio (Rs) only until a bend in the curve. For example, inFIG. 7A, the wrinkle index decreases at a steep slope until the scaled nozzle-paper ratio is about Rs≧0.85. Beyond this point, the wrinkle index (W) does not improve significantly and the napkin exhibits a satisfactory wrinkling index for some consumer applications. In other embodiments, a center-pull napkin dispenser10may be configured such that the scaled nozzle-paper ratio is Rs≧0.95. In still other embodiments, a center-pull napkin dispenser10may be configured such that the scaled nozzle-paper ratio is Rs≧1.2 or even Rs≧1.3.

The acceptable range of the scaled nozzle-paper ratio (Rs) is determined by various factors that may include the basis weight (bw), web caliper (cw), bond area, and/or nozzle cross-sectional area (AN). If the scaled nozzle-paper ratio (Rs) is too small, the napkin25may separate from the roll of napkins20before the napkin25fully passes through the nozzle opening121. If the scaled nozzle-paper ratio (Rs) is too large, the napkin25may not separate from the roll of napkins20as the napkin25passes through nozzle opening121(i.e., roping). Thus, the scaled nozzle-paper ratio (Rs) must be within the range that the napkin25will separate from the roll of napkins20, but will not separate from the roll of napkins too early in the dispensation process. In various embodiments, the scaled nozzle-paper ratio is Rs≦2.15. The shape of nozzle opening121may also affect the roping or early tearing characteristics of a roll of napkins20dispensed from a center-pull napkin dispenser10.

In various embodiments, the scaled nozzle-paper ratio (Rs) of a center-pull napkin dispenser10may be configured to dispense napkins25with a predetermined upper limit for the wrinkle index (W) for the napkins25. For example, in various embodiments, the scaled nozzle-paper ratio (Rs) may be configured such that the wrinkle index (W) of a substantial number of paper napkins25dispensed by the center-pull napkin dispenser10is W≦1.5, 1.0, 0.8, or 0.5.

FIGS. 7A-7Fillustrate how for paper napkin rolls made from various webs having a variety of basis weights, web calipers, various perforation bond areas, and/or other various web or napkin characteristics, a scaled nozzle-paper ratio (Rs) may correspond to preferred expected wrinkle index (Wx) given a nozzle12. Thus, in various embodiments, a center-pull napkin dispenser10may be configured such that the scaled nozzle-paper ratio may provide an expected wrinkle index of Wx≦1.5, 1.0, 0.8, or 0.5.

Exemplary Methods of Supplying Napkins in Various Embodiments

Various embodiments of methods of supplying napkins for a center-pull napkin dispenser10will now be discussed. Of course, it should be appreciated that a variety of methods for supplying napkins for a center-pull napkin dispenser10could fall within the scope of the invention given the disclosure contained herein.

In various embodiments, a nozzle12is selected that comprises a nozzle opening121configured for dispensing napkins therethrough. The nozzle opening121may be selected to define a nozzle cross-sectional area (AN) and/or a diameter (D) that corresponds to a diameter of a circle having the same area as the nozzle cross-sectional area (AN).

Further, in various embodiments, a roll of paper napkins is selected that defines a web width (ww), a web caliper (we), and a basis weight (bw). In various embodiments the length (1) of a paper napkin25is defined by the perforations present on the roll of paper25. As discussed above, the effective width (we) is approximated as we=ww/cos φ, where φ=40°, herein; however, other various approximations of the effective width could also be used without departing from the scope of the present invention. The apparent density (da) of the napkin25may be approximated, in various embodiments, by the basis weight divided by the web caliper, or da=bw/cw. Thus, in various embodiments, a cross-sectional material mass (X) for napkin25may be approximated as the product of the effective width and the apparent density, or X=we*da.

In various embodiments, at least one roll of paper napkins may then be selected such that the nozzle-paper ratio (R), defined by the nozzle cross-sectional area (AN) divided by the cross-sectional material mass (X), or R=AN/X, is within a predetermined range. In various embodiments, the at least one roll of paper napkins may be selected such that the scaled nozzle-paper ratio (Rs), defined as the nozzle-paper ratio (R) times a constant (C), or Rs=(AN/X)*C, is above a minimum value. For example, in embodiments in which the constant C=10,000, the scaled nozzle-paper ratio may be selected to be Rs≧0.85, 0.95, 1.2, or 1.3. In some embodiments, a roll of paper napkins20may be selected such that the wrinkle index (W) of a substantial number of paper napkins25dispensed by the center-pull napkin dispenser10is W≦1.5, 1.0, 0.8, or 0.5. In other embodiments, a roll of paper napkins may be selected such that the expected wrinkle index (Wx) of napkins that may be dispensed from the center-pull napkin dispenser10is Wx≦1.5, 1.0, 0.8, or 0.5.

The range of acceptable scaled nozzle-paper ratio (Rs) is limited by the ability of the center-pull napkin dispenser10to dispense napkin25. If the scaled nozzle-paper ratio (Rs) is too small, the napkin25may separate from the roll of napkins20before the napkin25has been dispensed through the nozzle opening121. If scaled nozzle-paper ratio (Rs) is too large, the napkin25will not separate from the roll of napkins20when the napkin25is dispensed (i.e., roping). However, the minimum and maximum acceptable nozzle-paper ratio (Rs) may be a function of the basis weight (bw), caliper (cw), bond area, nozzle cross-sectional area (AN), and/or nozzle shape. In various embodiments, the scaled nozzle-paper ration is Rs≦2.15.

In various embodiments, the at least one roll of paper napkins20may be placed inside the body11of the center-pull napkin dispenser10such that napkins25may be dispensed from the roll of paper napkins20via the nozzle12.

CONCLUSION