MXPA00000248A - Smooth bulky creped paper product - Google Patents

Abstract

A uniformly smooth Yankee side tissue product is provided. This tissue has the bulk of a creped tissue product but with a substantially smoother Yankee side surface of the sheet.

Description

BROAD AND SOFT CREPED PAPER PRODUCT BACKGROUND OF THE INVENTION Increasing the volume has been desirable in the manufacture of tissue paper for a long time. The increased volume provides economic benefits, advantages of product performance, and client preference advantages for the tissue product.

The volume of a sheet of paper is inversely related to the density of the sheet. By decreasing the density of the sheet, for example, the density values become smaller, the volume of the sheet will increase. The density of the paper sheet can be measured as grams per cubic centimeter (g / cubic centimeter) or a similar weight on volume measurement. Volume measurements for tissues are typically reported as a cubic centimeter / gram.

It has been known for a long time in the papermaking arts that the increased volume can be obtained by adhering a wet tissue of paper fibers to the surface of a Yankee dryer, or other similar smooth drying surface, drying the fabric to form a sheet of paper and then creping the sheet of paper from the surface of the dryer. Creping, however, can result in certain undesirable side effects. In particular, the creping increased the roughness of the sheet by creating a contour d surface having a series of ridges and troughs (valleys hills) running across the width (cross direction to the machine) of the sheet. Therefore, a creped sheet may feel rough, if not very rough, to a tissue user.

The present invention provides a new and useful form in which an increased volume of a creped tis is obtained, while the roughness of the surface associated with creping is avoided.

SYNTHESIS OF THE INVENTION In an embodiment of this invention, s provides a tissue made by creping a sheet of paper making fibers from a Yankee dryer; the sheet further comprises: a first side and a second side; the first side is in contact with the surface of the Yankee dryer; the second side is positioned away from the surface of the Yankee dryer; The first side of the sheet has a surface, said surface has a uniformly smooth appearance; a volume of at least (for example greater than or equal to) about 6 cubic centimeter / gram of at least about 7 cubic centimeter / gram, or at least about 8 cubic centimeter / gram; and a stretch of at least about 10% in the machine direction. This tissue may have the second side of the sheet composed of a creped pattern. This tissue can also be a single layer sheet mixed.

In another embodiment of this invention, there is provided a multi-layer tissue product having a smooth outer surface comprising: a first base sheet made by creping a sheet material from a Yankee dryer; the base sheet further comprises: a first lad and a second side; the first side is in contact with the surface of the Yankee dryer; the second side is placed out of the surface of the Yankee dryer; the first side of the base sheet has a smooth surface essentially free of any creped pattern; and the second side of the base sheet has a creped pattern, a second base sheet; the first and second base sheets are placed together to form a multi-stratified product; and the first side of the first base sheet constitutes the smooth outer surface of multiple stratum tissue. This multi-layer tissue may have the second base sheet further made by creping the base sheet from a Yankee dryer; the bas sheet further comprises: a first side and a second side; the first side is in contact with the surface of the Yankee dryer; the second side is positioned away from the surface of the Yankee dryer; the first side of the base sheet has a smooth surface; and the second side of the base sheet has a creped pattern, In yet another embodiment a single-layer base tissue sheet having a basis weight of about 10 to 25 grams per square meter, a volume d from about 6 cubic centimeters per gram to about 15 cubic centimeters per cubic meter is provided. gram, and a stretch from about 10% to about 50% in the machine direction; and comprises one side of the Yankee and one side of the Yankee; The Yankee side has a smooth surface, essentially free of any discernible crepe pattern.

In yet another embodiment a multi-layer tis made by creping the tissue from a dryer is provided and further comprises: an upper and a lower layer; the lower layer comprises: a first side; the first side is in contact with the surface of the Yankee dryer; the first lad has a uniformly smooth surface; the top layer comprises: a second side; the second side is positioned away from the surface of the Yankee dryer; the second side has a crepe pattern.

DRAWINGS Figure 1 is a schematic process flow diagram generally showing the manufacture of tissue paper products.

Figures 2A and 2B are photographs of the Yankee side surface of the paper sheet made according to the present invention. The lighting is oriented in the direction of the machine.

Figure 3 is a photograph of the Yankee side surface of a conventional creped sheet. The illumination is oriented in the direction of the machine.

Figure 4 is a perspective view of a sheet of paper of the present invention.

Figure 5 is a perspective view of a conventional crepe paper sheet.

Figures 6 and 7 are schematic drawings of a section of a paper making machine.

Figures 8, 9 and 10 are photographs of the paper taken at an amplification of 10x, 3/4 normal exposure to the light in the machine direction and at an angle of 15% from the horizontal.

DETAILED DESCRIPTION OF THE CURRENTLY PREFERRED INCORPORATIONS OF THE INVENTION Referring to Figure 1, which is a flowchart of the schematic process of a paper-making process, the cellulose fibers are prepared in a pulp redoubt (not shown) to form an aqueous solution of fiber and water, which It is mentioned as a supply or a supply solution. The supply is pumped to a chest 1 which can be mentioned as a draining chest. From the emptying box the supply is pumped to another holding box 2 which can be mentioned as a machine chest. From the machine chest the supply is pumped by the pump d fan 3 to the head box 4 of the paper making machine 5. On or before the fan pump, the supply is diluted with water. Usually and preferably the dilution is made with return water, mentioned as white water, from the papermaking machine. The flow of white water is shown by lines 6 and 7. Before the dilution and supply is mentioned as a thick supply, and after dilution the supply is mentioned as a water supply.

The water supply is then dewatered by the forming section 8 of the paper machine to form an embryo-weave of wet cellulose fibers. The wet fabric is then transferred to a dryer 9, which removes the agu from the wet tissue forming a sheet of paper. The dryer can be a Yankee dryer or another similar dryer having a smooth drying surface. The sheet of paper is then creped from the dryer by a doctor blade or creping knife 13. The paper sheet is then rolled onto a spool 10. The transfer area (shown by box 12) of the wet tissue to the surface of The dryer and the manner in which the wet fabric is transferred to and adhered to the surface of the dryer, are set forth herein in detail, the direction of the blade moving through the apparatus is referred to as the direction of the machine. Therefore the machine direction of the blade will coincide with a line parallel to the direction in which the blade is moved through the paper making machine. The transversal direction to the machine will be transversal to the machine direction.

It will be understood that Figure 1 is a general description of the papermaking process and is intended to illustrate the process and is in no way intended to limit the scope of the present invention. Many variations in the process and equipment are known to those skilled in the art of papermaking. Although the scheme generally shows a twin wire type forming section, other forming sections known in the art can be used. Additional components can also be added or removed from the process. For example, grids, filters refiners which are not illustrated, but can typically be placed between the pulp reducer and the head box. The transfer section 14 of the paper machine may not be present or may be expanded to include additional water removal devices. Additional passages can also be added to the machine after the dryer and before the reel, such as the use of a size press, even when additional drying is usually required after a size press application is used. The coating operations can also be carried out outside the machine. Additionally, the creping process of the sheet is a drying surface can be carried out outside the machine.

Referring again to Figure 1, the wet fabric is uniformly adhered to the surface of the Yankee. This can be achieved by using a solid rubber roll or a press roll of a similar type or a wet press roll. Alternatively, a felt 15 can be placed under the transfer fabric 11, or between the transfer tel 11 and the wet fabric 8 as shown in Figures 6 and 7. This felt has the effect of gently and uniformly joining the fabric wet to the surface of the Yankee. The felt requires applying uniform pressure against the sheet on the Yankee, without imparting any localized pressure or pressure patterns from the three-dimensional structure of the felt. For example, a suitable felt that can be used would be a non-woven adhesively bonded material, such as saturated fibrous compound 262 type S-46913, 178 # / 2880, produced by Kimberly-Clark. The example of this type of material and similar to the material used in the labels of Jean such as the label of Jeans Z6Z type S-46913.

The moisture content of the wet fabric at the point of adhesion to the Yankee should be around 20 about 60% solids, even though a higher or slightly lower percentage of solid can also be used depending on the temperature of the dryer. and the surface characteristics of the dryer. Additionally, creping aids or other process aids can be used on the surface of the Yankee dryer.

The paper sheets can be made of long paper fiber (soft wood), short paper fibers (hard wood), secondary fibers, other natural fibers, synthetic fibers or any combination of these or other fibers known to those skilled in the art. the art of papermaking to be used in the manufacture of paper. The long paper fibers are generally understood as having a length of about 2 millimeters or greater. Hardwood fibers including eucalyptus and maple fibers are especially suitable. As used herein, the term "paper fibers" refers to any and all of the above mentioned.

As used herein, and unless otherwise specified, the term "sheet" generally refers to any type of sheet of paper, for example, the tissue, the face towel, the bath tissue or other heavy weight basis product, creped or non-creped, mixed, creped or non-creped, mixed, multilayer (one, two, three or more layers) or single layer, and multiple strata or single stratum. As used herein and unless otherwise specified, the term "tissue" refers to all types of absorbent paper sheets of absorbent and soft paper sheets of lower base, whether known or not by that name, including without limitation the facial tissue and the tissue for retreat or bath.

The uniformly smooth creped tissue product of the present invention has a very low surface roughness but has a significant stretch and is smooth. For example, stretches in the range of about 15% to about 50% in the machine direction can be obtained for a base weight sheet of 15-20 grams per square meter (single layer). The tissue has very little or no discernible crepe or crepe pattern on the Yankee side of the sheet. The term "Yankee side" of the sheet refers to the side of the sheet that is adhered to the dryer and then creped from the dryer. This is evident when the tissue is seen with the naked eye as well as under a microscope at 10x.

As can be seen from the photographs of the Figures 2A and 2B (having the same amplification of the Yankee surface of the tissue falling within the scope of this invention with the light being oriented in the machine direction and at the oblique angle to the surface of the sheet) there is no crepad present . Instead of this, the surface of the sheet appears to be smooth with small elevations and random drops that have more appearance of skin or a non-woven fabric (at a magnification of zero). In contrast, the creping pattern is easily evident in the tissue shown in Figure 3 which is the same amplification and illumination of the Yankee side of the sheet.

The sheet of the present invention has the appearance of a uniform smooth surface on the Yanke side for an observer either without the aid or at lower amplifications (in the range of about 10x to about 20x). Thus, the sheet has a surface of the Yankee that is creped from the Yankee and that has the visual appearance of being uniform and smooth. The visual appearance of the Yankee side of the present invention is similar in appearance to the surface of a non-creped sheet of paper, such as, for example, writing paper or so-called bond.

The unique smooth surface characteristic of this tissue sheet can also be shown by a computer assisted with a topographic or profilometric analysis. This analysis focuses on the Yankee side of the sheet and provides * a three-dimensional analysis of the surface of the sheet.

Under this analysis, the sheets having base weight and similar creping blade conditions have a roughness value (Ra) of less than 30 μm, the asperez values of less than 25 μm and the roughness values of less than 15 μm for the side Yankee of the sheet. On the other hand, a conventional crepe tissue, having a similar supply, a similar bas weight, process conditions and creped blade conditions, and roughness test conditions may have a greater roughness value than that of the present invention for e Yankee side of the sheet.

Additionally, this analysis revealed that the uniformly smooth surface of the tissues has an essentially lower standard deviation in relation to the height of the surface of the sheet than does a conventional crepe tissue. That is, when you look at the variations in the height of the sheet surface, for example, the changes in the "z" axis, if you look at the surface of the sheet from above, those changes will be essentially more uniform than those of a tissue conventionally creped. Therefore, even when a tissue of the present invention can exhibit the same overall surface roughness value or even greater, the degree and severity of fluctuations in the z-value will be such that the tissue of the present invention will have a deviation. Essentially lower standard with respect to that value.

The roughness values are obtained by means of an optical system, such as the WYKO NT2000 scanning white interference microscope or a Cadeyes system and opposition when using pen-type or mechanical-type roughness measuring devices. U.S. Patent No. 5,779,965 describes the Cadeyes system, the description of which is incorporated herein by reference.

These features can also be further explained with reference to the drawings of the paper sheets shown in Figures 4 and 5. Figure 4 shows an example of a sheet 1 of the present invention while Figure 5 shows a conventional creped sheet 1 . Both drawings are amplified and exaggerated of the actual sizes of the leaves to more easily illustrate the structure of the leaves. The identifying numbers for the Figures are the same, unless specifically noted otherwise. The direction of the machine is represented by the x axis and the direction of the machine transverse by the y axis.

From these Figures it can be seen that the Yankee side of the sheet 1 is essentially different from the conventional sheet of Figure 5 and the present invention of Figure 4. Thus, if the variation in the height of the Yankee sides of these sheets is measured (for example in changes in the z-direction) the amplitude of those charges is essentially smaller for the present invention than for a conventional sheet. On both sheets the creping pattern can be seen on the outside of Yankee 3 of sheet 1. The creping pattern is also seen on the Yankee 2 side of the conventional creped sheet in Figure 5.

It has further been observed that with the tissues of the present invention an essentially smaller amount of the sheet surface is used to form the higher and lower portions of that surface. Therefore, in a conventional crepe sheet about 20-30% of the surface of the sheet was found in the upper portions of the creping rims or in the bottom of the creping troughs. In the tissue of the uniformly smooth surface of the present invention less than 10% of the sheet surface may constitute the highest and lowest points on the sheet.

The visually smooth side surface of the Yankee of the sheet of the present invention looks very similar to that of conventional writing paper or bond which has not been creped. This is shown by comparing Figures 8, 9 and 10. Figure 8 is a photograph of the Yankee side of the sheet of the present invention. The tissue has a stretch in the machine direction of about 39%. Figure 9 is a photograph of a sheet of commercially available bond paper manufactured by Kimberly-Clark. This sheet was not creped and has a stretch in the direction of the machine of less d around 5%. Figure 10 is a photograph of the Yanke side of a creped tissue that is commercially available from Kimberly-Clark. These photographs, figures 8, 9 and 10, as set out in the description of the section of drawings taken here were taken under the same amplification and lighting.

Claims (9)

R E I V I N D I C A C I O N S

1. A tissue made by creping a sheet of fibers to make paper from a Yankee dryer; The sheet also includes: a) a first side and a second side; b) the first side is in contact with the surface of the Yankee dryer; c) the second side is placed outwardly from the surface of the Yankee dryer; d) the first side of the sheet has a surface, said surface has a uniformly smooth appearance; e) a volume of at least about 6 cubic centimeters / gram; Y f) a stretch of at least about 10% in the machine direction.

2. The tissue as claimed in clause 1 characterized in that the volume is at least about 7 cubic centimeters / gram.

3. The tissue as claimed in clause 1 characterized in that the volume is at least d about 8 cubic centimeters / gram.

4. The tissue as claimed in clause 1 characterized in that the second side of the leaf comprises a creped pattern.

5. The tissue as claimed in clause 1 characterized in that the tissue is a single layer sheet mixed.

6. A multi-layer tissue product having a smooth outer surface comprising: i) a first base sheet made by creping a sheet of material from a Yankee dryer; The base sheet also includes: a) a first side and a second side; b) the first side being in contact with the surface of the Yankee dryer; c) the second side being positioned towards the surface of the Yankee dryer; d) the first side of the base sheet has a smooth surface essentially free of any creped pattern; Y e) the second side of the base sheet has a creping pattern; ii) a second base sheet; iii) the first and second base sheets are placed together to form a multi-stratified product; Y iv) the first side of. The first sheet of bas forms the smooth outer surface of the multi-layer tissue.

7. The multiple stratum tissue product as claimed in clause 6 characterized in that the second base sheet is further made by creping the base sheet from a Yankee dryer; the base sheet further comprises: a) a first side and a second side; b) the first side being in contact with the surface of the Yankee dryer; c) the second side being positioned towards the surface of the Yankee dryer; d) the first side of the base sheet has a smooth surface; Y e) the second side of the base sheet has a creped pattern,

8. A sheet of tissue having a basis weight d from about 10 to 25 grams per square meter, a volume of from about 6 cubic centimeters / gram to about 15 cubic centimeters / gram, and a stretch of from about 10% to about 50% in the direction of the machine; and comprising one side Yankee and one side of the Yankee; the Yankee side has a surface, said surface has a smooth appearance, said surface is furthermore essentially free of any discernible creping pattern.

9. A multi-layer tissue made by creping the tissue from a dryer and further comprising: i) an upper and a lower layer; ii) the lower layer comprises: a) a first side; b) the first side being in contact with the surface of the Yankee dryer; c) the first side has a uniformly smooth surface; iii) the upper layer comprises: a) a second side; b) the second side being positioned away from the surface of the Yankee dryer; Y c) the second side has a creping pattern. E S U M E N A uniformly smooth Yankee-side tissue product is provided. This tissue has the volume of a creped tissue product but with an essentially smoother sheet surface on the side of the Yankee.