SHEET SUBSTRATE WITH SURFACE PATTERNS TO FACILITATE SHEET FEEDING

Abstract

A paperboard sheet and a method of using the paperboard sheet is provided in which a surface of the paperboard sheet provides a pattern of indentations, the indentations reducing the surface area between adjacent sheets to facilitate the transfer of a top sheet from a stack of similar sheets.

Description

RELATED APPLICATIONS

This application claims the benefit of U.S. Application Ser. No. 62/720,233 filed on Aug. 21, 2018 and which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention is directed towards a paperboard slip sheet and tier sheet substrate having a plurality of indentations on a least one substrate surface, the indentations increasing the surface area of the substrate and lowering the coefficient of friction between adjacent sheets in a plurality of stacked sheets and allowing improved air flow between adjacent sheets. The lower coefficient of friction allows for an easier separation of sheets during sheet feeding operations.

BACKGROUND OF THE INVENTION

It is well known in the art to provide stacked sheets of paperboard slip sheets or tier sheets which may be coated or uncoated. As the stacked sheets are individually removed and processed using automated sheet feeders, the displaced sheet will often adhere to the adjacent stacked sheet. Efforts to prevent the “sticking” of the adjacent sheets have included specialized sheet feeders with preciously placed rollers or using vacuum systems that are designed to minimize the problem. Other efforts have included the use of coatings or surface agents applied to the sheets such as calcium chloride, starch, or other additives that are designed to lower the coefficient of friction.

One example of a slip sheet and tier sheet that is known in the art can be found in reference to U.S. Pat. No. 4,708,247, entitled “Slip Sheet” and which is incorporated herein by reference.

However, there remains room for improvement and variation in the art.

SUMMARY OF THE INVENTION

It is one aspect of at least one of the present embodiments to provide for a method of forming and separating sheets of paperboard, such as slip sheets or tier sheets, within commercial sheet feeding apparatuses and operations.

It is yet another aspect of at least one embodiment of the present invention to provide for a paperboard sheet that is adapted for placement within a sheet feeder and which comprises a paperboard substrate having a first surface and a second surface, at least one of the first surface or the second surface having a textured pattern formed on the sheet surface, the textured pattern reducing the contact surface area between adjacent sheets, the reduced contact surface area being at least about 10 percent less than untextured sheets.

It is yet another aspect of at least one embodiment of the present invention wherein providing a single sheet further includes providing a sheet in which both a first surface of the sheet and a second surface of the sheet define a pattern for the modified sheet.

It is yet another aspect of at least one embodiment of the present invention to provide the textured pattern that reduces the surface area contact between adjacent flat sheets by at least about 15%.

It is yet another aspect of at least one embodiment of the present invention to provide a textured pattern formed on first surface of the sheet and a second surface of the sheet, the pattern being raised relative to a first surface of the sheet and being recessed relative to the second surface of the sheet.

It is yet another aspect of at least one embodiment of the present invention to provide a paperboard sheet adapted for use as a slip sheet or tier sheet comprising; a paperboard substrate having a first surface, a second surface, and a thickness of substantially about 0.010 to about 0.012 inches; a raised textured pattern formed on an upper surface of the sheet, the textured pattern reducing the contacting surface area with an adjacent sheet in contact with the first surface by at least about 10%; a second textured pattern formed on the second surface of the sheet, the second pattern being a recessed pattern formed integral with the raised pattern wherein when the paperboard sheets are placed in a stacked arrangement, the contact area between a first surface of one sheet and a second surface of an adjacent sheet reduces a surface area contact between the adjacent sheets by at least about 10%.

It is yet another aspect of at least one embodiment of the present invention to provide the textured pattern formed on an embossed region on the paperboard sheet, wherein a width of the embossed line forming the pattern is about 1/16^th of an inch.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A fully enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings.

FIG. 1 is a view of one non-limiting embodiment of a sheet having a textured pattern.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present invention are disclosed in the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present invention, which broader aspects are embodied in the exemplary constructions.

It is to be understood that the ranges mentioned herein include all ranges located within the prescribed range. As such, all ranges mentioned herein include all sub-ranges included in the mentioned ranges. For instance, a range from 100-200 also includes ranges from 110-150, 170-190, and 153-162. Further, all limits mentioned herein include all other limits included in the mentioned limits. For instance, a limit of up to 7 also includes a limit of up to 5, up to 3, and up to 4.5.

As used herein, the term “substantially about” is given a meaning of plus or minus 10 percent of the stated value unless otherwise indicated.

In describing the various FIGURES herein, the same reference numbers are used throughout to describe the same material, apparatus, or process pathway. To avoid redundancy, detailed descriptions of much of the apparatus once described in relation to a FIGURE is not repeated in the descriptions of subsequent FIGURES, although such apparatus or process is labeled with the same reference numbers.

As seen in reference to FIG. 1, a paperboard sheet 10 is provided which may be used as a slip sheet or tier sheet. Sheet 10 can be formed from a single or multiple ply arrangement and may include up to 100% recycled fiber chip board. Sheet 10 can also be coated or uncoated. In one preferred embodiment, the upper sheet surface 11 has a raised embossed pattern 12 seen here as a repeating pattern of squares applied in a substantially diagonal pattern to the surface 11. A corresponding debossed pattern of depressions is formed on the lower surface of sheet 12 the depression pattern being integral to the raised pattern 12 of the top surface. When stacked, the placement of the debossed lower surface of a top sheet onto a similar pattern of an embossed raised surface of the adjacent, provides a region of reduced contact between the adjacent stacked sheets compared to two opposing smooth sheet surfaces.

As seen in FIG. 1, a pattern 12 of a textured surface is formed on at least one surface of sheet 10. The pattern 12 can be created on the sheet surface using a variety of techniques including embossing rollers, die cutters, platen presses, or cutting/scoring tools.

The pattern 12 increases the surface area of the treated surface of the paperboard sheet 10. By increasing the surface area of the sheet, the amount of surface area contact with respect to the pattern 12 to an adjacent sheet surface is correspondingly decreased. The decrease in the amount of contact surfaces lowers the coefficient of friction between adjacent sheets and allows the mechanical separation of a stacked supply of sheets using a vacuum separation or a sheet feeder, to be accomplished more easily and with less jamming or feeding of multiple sheets. The pattern also provides a space between sheets that allows air flow between the sheets to facilitate sheet separation, particularly when using vacuum separation technology.

Preferably, it is desirable to provide a surface pattern 12 in which the contact surface of the pattern 12 with an adjacent sheet is lowered by at least about 10% and more preferably between 15% to about 50%. The lowering of the percentage of contact surfaces between adjacent sheets allows the separation of stacked sheets to be done more easily and with fewer instances of non-separation of sheets.

In some embodiments, the pattern 12 can be comprised of a raised pattern on only one surface. In other embodiments, the pattern 12 involves modifying the sheets surface such that only depressions are formed below the initial sheet surface. The pattern can include lines, overlapping lines, stippling, embossed logo patterns, and other geometric or random patterns. Ideally, the surface area contact between the adjacent sheets is reduced by at least about 15% in order to improve sheet separation and may include sheets having a raised pattern on one surface to a recessed pattern on a lower surface.

In accordance with the invention, it has been found useful for the embossed pattern to still allow for the flat stacking of sheets. As a general rule, it is undesirable to create an uneven height differences on a portion of a sheet that results in a shingling of stacked sheets.

In accordance with this invention, it has been found that not all portions of a sheet need to be subjected to the pattern forming process. For instance, a pattern can be applied to just a boundary edge margin of a sheet, localized to a center portion of a sheet, be in the form of a series of parallel strips, a large X pattern, or other configurations such that selected portions of the sheet surface are modified so as to bring about the desired reduction in the surface area contact between the sheets and thus result in a lower coefficient of friction between the sheets.

For instance, the pattern 12 seen in FIG. 1 could be squares or a diamond shaped chevron type pattern in which each individual square or other polygon shape has an interior surface area of between about 3.6 to about 4.2 square inches.

The depth/height of the score lines for embossing or debossing can be varied, For instance, a 1/16 of an inch raised/depth dimension has been found to work well with slip sheets having a thickness of between about 0.025 inches to about 0.050 inches. It has further been found that using a 1/16 inch width profile to the score or embossed regions has sufficient dimensions with respect to the paper texture such that adjacent sheets will not register or nest within similar overlapping patterns. By not forming a tight nested pattern, the ease of separation is facilitated when a top sheet is separated from a lower adjacent sheet.

Although preferred embodiments of the invention have been described using specific terms, devices, and methods, such description is for illustrative purposes only. The words used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those of ordinary skill in the art without departing from the spirit or the scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged, both in whole, or in part. Therefore, the spirit and scope of the invention should not be limited to the description of the preferred versions contained therein.

Claims

1. A process of improving the separation of a single sheet in a stack of a plurality of similar sheets comprising:

providing a single sheet, a first surface of the sheet defining a pattern of textured surface features, there by providing modified sheet;

stacking a plurality of the modified sheets;

displacing a single sheet from the plurality of stacked sheets, the single sheet having a lower coefficient of friction with an adjacent sheet, thereby lessening the separation force needed for sheet separation.

2. A paperboard sheet adapted for placement within a stack supply of similar sheets in a sheet feeder comprising:

a paperboard substrate having a first surface and a second surface;

a textured pattern formed on at least the first surface of the sheet, the textured pattern reducing the surface area contact within an adjacent flat sheet by at least about 10%.

3. The process according to claim 1 wherein step of providing a single sheet further includes providing a sheet in which both a first surface of the sheet and a second surface of the sheet define a pattern for the modified sheet.

4. The paperboard sheet according to claim 2 wherein the textured pattern reduces the surface area contact between adjacent flat sheets by at least about 15%.

5. The paperboard sheet according to claim 2 wherein the textured pattern is formed on first surface of the sheet and a second surface of the sheet, the pattern being raised relative to a first surface of the sheet and being recessed relative to the second surface of the sheet.

6. A paperboard sheet adapted for use as a slip sheet or tier sheet comprising:

a paperboard substrate having a first surface, a second surface, and a thickness of substantially about 0.010 inches;

a raised textured pattern formed on an upper surface of the sheet, the textured pattern reducing the contacting surface area with an adjacent sheet in contact with the first surface by at least about 10%;

a second textured pattern formed on the second surface of the sheet, the second pattern being a recessed pattern formed integral with the raised pattern wherein when the paperboard sheets are placed in a stacked arrangement, the contact area between a first surface of one sheet and a second surface of an adjacent sheet reduces a surface area contact between the adjacent sheets by at least about 10%.

7. The paperboard sheet according to claim 6 wherein the textured pattern is formed from an embossed region on the paperboard sheet, and a width of the embossed line forming the pattern is about 1/16th of an inch.