WO2001059210A1

WO2001059210A1 - Tissue embossing felt

Info

Publication number: WO2001059210A1
Application number: PCT/US2001/003824
Authority: WO
Inventors: Paul H. Sutherland
Original assignee: Astenjohnson Inc.
Priority date: 2000-02-09
Filing date: 2001-02-06
Publication date: 2001-08-16
Also published as: AU2001234863A1; WO2001059210A8

Abstract

a papermaking fabric (10) for embossing tissue paper has three layers. One layer is a woven base layer (12) similar to that of a press fabric. Another layer is a batt layer (14) also similar to that found in a traditional press fabric. The third layer is a non-woven embossing layer (16), which has an irregular surface to imprint the paper web. According to the invention, the embossing layer is intermediate between the base layer and batt layer, secured by the needling of the batt layer. The fabric embosses the paper web while aiding in the dewatering process.

Description

TISSUE EMBOSSING FELT

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a papermaking fabric. More specifically, it relates to a fabric used in tissue making machines. Most specifically, the invention relates to a tissue paper embossing fabric.

Description of the Related Art

Tissue paper is used in sanitary and hygienic products such as toilet paper, facial tissue, sanitary napkins, paper towels, etc. The industry produces six million tons of hygienic tissue paper per year in the U.S. alone. Tissue paper is distinguished from other paper products by its softness, bulk, and absorbency. Because tissue paper is more delicate than other papers, it is generally made on special tissue making machines. Many of these machines are designed to create softness, bulk and absorbency by embossing the paper web with depressions or mounds where the density of paper fibers differs from the rest of the paper. During the papermaking process, the paper web is transferred from the forming section to an embossing fabric . In some cases the fabric carries the paper web through a vacuum box which pulls the web into depressed areas of the fabric to make an impression on the paper web. Some employ an extra press roll, for both dewatering and imprinting the paper web, prior to transferring the paper web to the dryer section. In some cases, especially where embossing has not been used, the tissue is creped using a doctor blade to create softness and bulk. Embossing fabrics have been made using a base fabric, and a resinous top layer which defines deflecting members for leaving impressions in the paper web. These fabrics have employed both a woven base fabric and a non-woven embossing layer without the benefit of a batt layer. Although these fabrics have been well suited to embossing the paper web, they lack the desired conveying and drying ability.

The tissue making machines generally lack a traditional press section having a conventional batt-on-mesh press fabric for removing water from the paper web prior to the dryer section. Traditional press fabrics have a base fabric and a surface batt layer. The combination is thought to reduce paper marking and improve dewatering.

Through the years, papermaking fabrics have continued to evolve as the papermaking machines and final products demand more of the fabrics. In some cases, foam has been added to press fabrics to enhance dewatering capabilities. Foam enhancement has been utilized with and without needled batt fibers. In some cases, a foam layer has been added between the base fabric and a needled batt layer. These fabrics, however, have not been designed for embossing a tissue paper web.

In the evolution of papermaking fabrics, layers of non- woven sheets have been joined together to form a fabric. The several layers define drainage apertures and several different fabric characteristics such as strength, chemical resistance, abrasion resistance, etc. The non-woven sheets have been embossed for better control of the fabric in the paper machine, rather than for imprinting the paper web.

Traditional embossing fabrics require a coarse structure to transfer an impression to the paper web. This requirement has led to the loss of both pick-up and dewatering properties found in press fabrics. The art is in need of an embossing fabric that will overcome these problems and reduce the amount of time spent in the costly dryer section.

SUMMARY OF THE INVENTION

The present invention is an embossing fabric having a base layer, an embossing layer, and a batt layer overlying the embossing layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a partial cut-away, plan view of an embossing

fabric of the present invention.

Figure 2 is a cross sectional view of a fabric as seen

along line 2-2 of Figure 1 of the present invention.

Figure 3 is a schematic representation of one embodiment of a tissue paper making machine which uses the embossing fabric of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment will be described with reference to the drawing figures where like numerals represent like e1ements throughout . A papermaking fabric 10 for embossing the paper web in

a tissue making machine according to the present invention has three fabric layers. The fabric 10 may be formed into an endless belt by conventional seaming or weaving techniques. Batt layer 14 and embossing layer 16 are affixed to base

fabric 12. Preferably, the base fabric 12 is woven as a

traditional press fabric of monofilament yarns 13 as is well

known in the art. Similarly, the batt layer 14 may be the same as that found in traditional press fabrics. The batt layer helps draw water from the paper web 30, and reduces

unwanted paper marking.

The embossing layer 16 creates the impression found in

the final tissue paper 32. This layer is preferably non- woven. However, the embossing layer also may be knitted, air- layered or otherwise produced as a random sheet. The surface is irregular and may be oriented into a pattern. As the fibers are carried on the belt, they arrange themselves differently at the surface irregularities. The result is altered fiber density and orientation which create the desired qualities in tissue paper. Unlike conventional embossing fabrics, the present invention has, in addition to the embossing layer, both a woven base 12 and a needled batt layer 14, which allow the fabric 10 to function as a press fabric to help dewater the paper web while simultaneously embossing it.

In order to permit drying of the paper web, the embossing layer 16 is preferably porous. This is most easily and efficiently accomplished when the surface irregularities actually form perforations or apertures 18 which pass completely through the embossing layer. The surface irregularities act as means for transferring impressions to the paper web 30 while directing water away from the paper web

30 for drying purposes.

According to the present invention, the embossing layer 16 is sandwiched between the base fabric 12 and the batt layer

14. In this intermediate position, the embossing layer 16

never touches the paper web 30 directly. Instead, the batt

layer 14, as in traditional press fabrics, makes direct

contact with the paper web 30. The paper web 30, however, still deforms consistent with the surface irregularities in the embossing layer 16 as it passes through the vacuum box 42

and press rolls 46. The drying and conveying capabilities of a fabric thus constructed approach that of traditional press fabrics which are not normally used in embossing operations. In creating the fabric, the intermediate embossing layer 16 is secured to the base fabric 12 when the batt is needled to the base layer through the embossing layer. In the tissue making process, the paper web 30 is formed in the forming section of the tissue making machine and carried on a forming fabric 40 to the embossing section of the

machine. Here, it is transferred to the embossing fabric 10. According to the present invention, the paper web 30 is more

easily conveyed by the present embossing fabric 10 because of

the batt layer 14 which is not found in traditional embossing

fabrics. The web 30 is then carried through a vacuum box 42.

As the web 30 passes through the vacuum box 42, it conforms

to the surface of the fabric causing the web 30 to deform into

the surface irregularities of the embossing layer 16. The

deformation of the paper web 30 causes the paper fibers to reorient themselves into high and low density areas which form visual and tactile impressions in the paper web 30 which impart softness and bulk in the final tissue product. Simultaneously, water is pulled out of the paper web 30,

wicked away by the batt layer 14, and ultimately passed

through the base fabric 12, just as in traditional press fabrics. Conventional embossing fabrics lack this feature. The paper web 30 may then be further dried by through-air

dryers 44 or similar means. This, however, may be unnecessary due to the greater dewatering ability of the present embossing fabric. Preferably, the embossed web 30 is then carried through a press or impression roll 46, which again forces the paper web 30 to deform into the irregularities of the

embossing layer 16 to re-imprint the tissue web 30. The paper

web 30 is then transferred to the dryer section, where it is dried to its final form. Any conventional dryer may be used, such as a Yankee dryer 48, as shown in Figure 3. As with

traditional tissue making operations, the paper web 30 optionally may be creped, through traditional means such as a doctor blade 50, as it is removed from the dryer section.

Use of the present embossing fabric reduces the amount of time and energy needed in the dryer section by improving the dewatering capability of the embossing fabric over those used in traditional embossing operations.

Claims

I claim :

1. A tissue paper embossing fabric comprising: a base layer; an embossing layer having an irregular surface; and a batt layer overlying the embossing layer and affixed to the base layer.

2. The fabric of claim 1 wherein said irregular surface defines perforations passing completely through said embossing layer.

3. The fabric of claim 1 wherein said irregular surface of said embossing layer forms a pattern.

4. The fabric of claim 1 wherein said embossing layer is non-woven.

5. The fabric of claim 1 wherein said embossing layer is knitted.

6. The fabric of claim 1 wherein said embossing layer is air-layered to produce a random sheet.

7. The fabric of claim 1 wherein said embossing layer is secured by needling of said batt layer to said base layer through said intermediate embossing layer.