MX2011007044A

MX2011007044A - Tissue with improved dispersibility.

Info

Publication number: MX2011007044A
Application number: MX2011007044A
Authority: MX
Inventors: Michael Alan Hermans; Kristina Fries Smits
Original assignee: Kimberly Clark Co
Priority date: 2008-12-29
Filing date: 2009-11-25
Publication date: 2011-07-20
Also published as: WO2010076686A3; US20100163197A1; GB2478491A; WO2010076686A2; GB201111298D0

Abstract

Soft tissue sheets, such as bath tissues, are provided with increased dispersibility and fiber opacity efficiency, while maintaining suitable strength, by the addition of acid-treated seed fibers to the fiber furnish.

Description

PAPER WITH IMPROVED DISPERSIBILITY FIELD OF THE INVENTION The invention relates to sheets of soft paper, such as toilet paper with dispersibility and improved fiber opacity efficiency while maintaining the appropriate strength by the addition of acid-treated fiber grains.

BACKGROUND OF THE INVENTION Most consumers want a toilet paper that is not only strong enough for cleaning purposes, but they also want comfort in their mind that the paper will disperse and go through the toilet and not It will get stuck in the sewer or septic lines. While commercially available toilet papers are dispersed, there is an opportunity to improve them. Unfortunately, the increased dispersion usually arrives with a decrease in strength, which is undesirable. Therefore there is a need for bath papers having adequate strength with increased dispersion while at the same time exhibiting good opacity for the hand protection perceived in use.

SUMMARY OF THE INVENTION It has now been discovered that soft papers, such as toilet paper, can be manufactured with improved strength and dispersibility compared to commercially available toilet paper products. In addition, the efficiency of fiber opacity (defined later in this document) can also be improved.

Herein in one aspect, the invention resides in a soft paper having a rigid dry basis weight of about 15 to about 35 grams per square meter, a geometric average tensile strength of about 500 to about 1000 grams per 3. inches (7.62 cm) wide and a Dispersibility (hereinafter defined) of approximately 1.5 cycles or less.

In another aspect, the invention resides in a soft paper having a rigid dry basis weight of from about 15 to about 35 grams per square meter and from about 0.5 to about 5 percent dry weight of an Enhanced Fiber Additive (from hereinafter defined), said paper having an average geometric tensile strength of about 500 to about 1000 grams per 3 inches (7.62 cm) wide and a Dispersibility of about 1.5 cycles or less.

For purposes of this document, a "soft fabric" is a sheet of fibers for making cellulosic paper suitable for use as a toilet paper. Said sheets of soft paper are characterized by a relatively high volume and low stiffness (as measured by the geometric mean inclination). More specifically, the volume of soft paper sheet can be about 3 cubic centimeters or more per gram of fiber, more specifically from about 4 to about 20 cubic centimeters per gram of fiber (cc / g) and even more specifically from about 5 to approximately 10 cc / g. The geometric mean tilt of the soft paper sheet can be from about 1 to about 10 kilograms, more specifically from about 1.5 to about 8 kilograms and even more specifically from about 2 to about 6 kilograms.

For purposes of this document, an "Enhanced Fiber Additive" is a known seed-based fiber additive, such as fibers derived from corn and soybeans, that have been modified by acid treatment. The acid treatment can optionally be followed by a mild acid chlorite solution, a peroxide solution or a combination of both. The Resultant Enhanced Fiber Additive is high in cellulose, which increases fiber-to-fiber bonding and is normally used as a resistance agent in high-density papers. The production and uses of Enhanced Fiber Additives are described in U.S. Patent No. 6,902,649 B1 entitled "Enhaced Fiber Additive, and Use", issued June 7, 2005 to Satyavolu et al., which is incorporated in this document as a reference in its entirety. A commercially available line of Enhanced Fiber Additive is available from Cargill Incorporated, Minneapolis, Minnesota, under the trademark HemiForce ™. For purposes of this invention, the amount of Enhanced Fiber Additive in the soft paper can be from about 0.5 to about 5 weight percent in seo, more specifically from about 0.5 to about 4 weight percent dry and even more specifically from about 1 to about 3 weight percent.

The rigid dry basis weight of the soft papers of this invention can be from about 15 to about 15 to about 35 grams per square meter (gsm), more specifically from about 15 to about 30 gsm and more specifically from about 15 to about 25. gsm The geometric tensile strength (GMT) of the soft papers of this invention can be from about 500 to about 1000 grams by 3 inches (7.62 cm) wide, more specifically from about 500 to about 900 grams by 3 inches (7.62 cm) of wide and even more specifically from about 550 to about 650 grams by 3 inches wide (7.62 cm). For purposes of simplicity, the GMT is sometimes reported as "grams".

The dispersibility of the soft papers of this invention may be about 1.5 cycles or less, more specifically from about 0.5 to about 1.5 cycles, more specifically from about 0.5 to about 1.0 cycles, and even more specifically about 1.0 cycles.

The opacity of the soft papers of this invention can be from about 42.0 to about 47.0 percent, more specifically from about 42.0 to about 46.5 percent and even more specifically from about 42.5 to about 46.5 percent.

The efficiency of the opacity of the fiber for the papers of this invention which is the proportion of the opacity divided by the rigid dry basis weight and is a measure of the efficiency of the fibers in providing opacity to the paper sheet, can be approximately 2.5 percent / gsm or greater, more specifically from about 2.5 to about 3.0 percent / gsm, and even more specifically from 2.56 to 2.70 percent / gsm.

Suitable fibers for papermaking particularly include, without limitation, softwood fibers and hardwood. As used herein, the term "supply" means fibers for making paper, such as softwood and hardwood fibers used to make the paper, excluding other delivery components or additives, such as EFA. The amount of softwood fibers in the supply can be from about 5 to about 40 percent dry weight, more specifically from about 10 to about 40 percent, more specifically from about 10 to about 30 percent and even more specifically from about 10 to about 20 percent. Similarly, the amount of hardwood fibers in the supply can be from about 60 to about 95 percent dry weight, more specifically from about 60 to about 90 percent dry weight, more specifically from about 70 to about 90 percent. and even more specifically from about 80 to about 90 percent dry weight. Relatively speaking, larger amounts of softwood fibers will increase the tensile strength, while higher levels of softwood fibers will increase the smoothness and opacity of the surface.

In the interests of brevity and conciseness, any range of values established in this specification contemplates all values within the range and is to be constructed as the support of the written description for the claims by pointing out any subrange that has terminal points that are a complete number or otherwise of similar numerical numbers within the specific range in question. By means of a hypothetical illustrative example, a description in this specification of a range of from 1 to 5 will be considered to support the claims for any of the following ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4 and 4-5. Similarly, a description of this specification from a range of 0.1 to 0.5 will be considered to support the claims for any of the following ranges: 0.1-0.5; 0.1-0.4; 0.1-0.3; 0.1-0.2; 0.2-0.5; 0.2-0.4; 0.2-0.3; 0.3-0.5; 0.3-0.4; and 0.4-05. In addition, any value preceded by the word "approximately" is to be constructed as the support of the written description for the value itself. By way of example, a range of "from about 1 to about 5" is also to be interpreted as described and which provides support for a range of "from 1 to 5", "from 1 to approximately 5" and "from approximately 1 to 5".

DETAILED DESCRIPTION OF THE INVENTION Test Methods As used herein, the sheet "volume" is calculated as the "caliper" coefficient of the sheet (hereinafter defined), expressed in microns, divided by the basis weight expressed in grams per square meter. The resulting leaf volume is expressed in cubic centimeters per gram. More specifically, the caliper of the sheet is the representative thickness of a single sheet measured in accordance with the TAPPO test methods T402"Standard Conditioning and Test Atmosphere for Paper, Cardboard, Pulp Sheets and Related Products" and T41 1 om-89"Thickness (gauge) of Paper, Cardboard and Combined Cardboard" with Note 3 for stacked sheets. The micrometer used to perform 7411 om-89 is an Emveco 200-A Paper Calibrator Tester available from Emveco, Inc. Newberg, Oregon. The micrometer has a 2-kilo-Pascal load, a pressure foot area of 2500 square millimeters, a pressure foot diameter of 56.42 millimeters and a delay time of 3 seconds and a decrease ratio of 0.8 millimeters per second. .

As used herein, the "geometric average tensile strength" is the square root of the product of the tensile strength of machine direction multiplied by the tensile strength of the cross machine direction. The "tensile strength of machine direction (MD) is the peak load (grams-force) per 3 inches (76.2 mm) of the sample width when a sample is pushed to break in the machine direction. Extendible Machine Direction (DM) "is the peak load by 3 inches (76.2 mm) of the sample width when the sample is pulled to break in the machine direction." Expansion "is the percentage of elongation of the sample at the point of rupture during the extension test The procedure for measuring the tensile strength is as follows.

Samples for tensile strength testing are prepared by cutting a strip 3 inches (76.2 mm) wide by 5 inches (127 mm) long in machine direction orientation (DM) or cross machine direction (DC ) using a JDC Precision Sampling Cutter (Thwing-Albert Instrument Company, Philadelphia, PA, Model No. JDC 3-10, Serial No. 37333). The instrument used to measure the extensible resistors is an MTS from Systems Sintech S, Serial No. 6233. The data acquisition program is MTS TestWorks® for Windows Ver. 3.10 (MTS Systems Corp. Research Triangle Park, NC). The cell load is selected from a maximum of Newton 50 or Newton 100 depending on the resistance of the sample being tested, so that most values of the peak load fall between 10-90% of the full scale value of the cell of cargo. The gauge length between the jaws is 0.65 inches (12.7 mm). The speed of the inner protrusion of the piston is 10 ± 0.4 inches / min (254 ± 1 mm / min) and the breaking sensitivity is set at 65%. The sample is placed in the jaws of the instrument, centered both vertically and honorably. The test is then started and finished when the specimen breaks. The puco load is recorded as "extensible DM resistance" or "tensile DC resistance" of the specimen depending on the direction of the sample being tested. At least six (6) representative specimens are tested, each product or sheet taken "as is" and the arithmetic average of all individual specimen tests is the tensile strength DM or DC for the product or sheet.

The "geometric mean inclination" (MG inclination) is the square root of the product of the extendable tilt of the machine direction and the extendable tilt of the cross machine direction. The extensible tilt is at least the regression inclination of squares of the extension / load curve described above measured over the range of 70-157 grams (force). The slope is in kilograms per unit extension (ie 100% tension) for a sample width of 76.2 mm (3 inches), but for simplicity purposes it is sometimes reported in this document as "kilograms".

As used herein, "Dispersibility" is a measure of the propensity of a paper product to break apart when placed in water under gentle agitation. It was determined by placing a sample of the product in the turbid water box and observing the dynamic breakdown of the sample as the turbid water box moves back and forth (cycles). For toilet paper rolls, the sample to be tested is a simple "sheet" that for purposes of this document and well understood within the paper industry, is the segment of the sheet of toilet paper located between consecutive lines of perforation. . It may consist of one or more leaves. Said sheets are typically approximately 4 square inches (10.16 cm). The actual size, however, is not particularly important since the size of the turbid water box is large enough to accommodate any known sheet of paper. For purposes of testing the base sheets of the paper sample, which have not become the actual final product, a sample of 4 inches by 4 inches (10.16 cm x 10.16 cm) is sufficient.

The turbid water box used for the dynamic breaking of the sample consists of a plastic box that has internal dimensions measuring 18 inches wide (as seen from the front), 12 inches deep (30.48 cm) (from front to back) and 6.5 inches high (16.51 cm). It is constructed of Plexiglas® 0.5 inches thick (1.27 cm) and is provided with a tightly fitting lid. The turbid water box rests securely on a swinging platform and swings back and forth from the short side (12-inch end) to the short side (12-inch opposite end 30.48 cm). The lower part of the platform joins an alternative movement cam. In operation, the rotational movement of the cam cyclically raises one side of the platform and therefore also decreases the corresponding side of the turbid water box by rotating in the center of the box. The amplitude of the rolling motion of one side of the turbid water box is ± 2 inches (5.08 cm) (a range of 4 inches (10.16 cm) from above to the bottom of the swing cycle). The rotating speed of the cam is set at a constant speed of 26 revolutions per minute (± 2 revolutions per minute), resulting in 43 cycles of turbid water per minute. For purposes of this document, a "cycle" consists of an "up and down" movement of the turbid water box.

Before the test, the turbid water box is filled with 2000 ml ± 20 ml of a soaking solution. The soaking solution consists of distilled water mixed with a tablespoon of 0.25 ml of baking soda to keep the pH of the soaking solution at more than 7. The temperature of the soaking solution is maintained at 23 ° C ± 3 ° C . The solution is drained and the chamber of the box is rinsed and filled between each specimen characterization. To carry out the test, the paper sample is placed flat on the surface of the water in the turbid water box and the turbid water box starts immediately. The breaking of the sample in the turbid water box is observed visually and the number of complete cycles required to separate the sample into two separate pieces was recorded. (For multiple sheet products, the separation of the sheets does not constitute separation of the sample into two separate pieces for purposes of this sample, instead, at least one of the sheets must be separated into two separate pieces). Five duplicates of the paper sample were tested. The observed number of cycles required to break the test samples was averaged to achieve a Dispersibility value (in "cycles") for the product sample.

As used in this document, "opacity" is measured using a Technibrite Micro TB-1C tester, which is well known in the paper industry, available at Techidyne Corporation, 100 Quality Avenue, New Albania, Indiana; USA The Technibrite Micro TB-1 C tester, which is a dual beam optical system, is a fully automatic microprocessor-controlled instrument that provides brilliance, color, opacity and fluorescence in accordance with ISO and other international standards. The tests were carried out in a standard laboratory atmosphere (23 ° C ± 1 ° C and 50% ± 2% humidity) following the instructions for the instrument. To measure the opacity of the paper, the QC routine is used with the black body cup and with the Y (green) filter in the active position. When measurements are taken, the operator should avoid taking the readings in areas of the sample that contain impressions or perforations. Measurements should be taken on the outside of the sheets (the side of the sheet that consumers should see). Fifteen representative samples should be tested and the results averaged to obtain a value for the particular product. The measurement values represent the reflectance and are expressed as a percentage.

Examples To further illustrate this invention, a number of papers are produced using conventional wet-press creping technology, such as the method described in US Patent No. 6,368,454 entitled "Method of Making Single Soft Sheet Paper" issued on April 9, 2002 to Dwiggins et al. (without engraving), that by means of this The document is incorporated as a reference. Unless stated differently, the method for making used particular paper is not critical.

Example 1 (Invention) Base sheet for single sheet bath paper was produced in a conventional manner on a pilot scale paper machine. More particularly, a paper web was formed into a forming fabric, transferred to a web and subsequently transferred to a Yankee dryer in a conventional manner. The tissue paper was dried at approximately 95 percent consistency in the Yankee dryer and creped using standard creping technology. The resulting creped paper sheet was wound on a master roll for testing.

The paper supply was a mixed supply comprising hardwood eucalyptus (HW) fibers and refined northern softwood kraft fibers (SW). Before the formation of the fabric, the softwood fibers of the north were pulped for 30 minutes at 2.5 percent consistency, while the hardwood fibers of eucalyptus were pulped at 2 percent consistency. The softwood fibers of the north were refined for 5 minutes. The pulp blend (expressed as the percentage of dry dry weight) was 39.2 percent SW, 58.8 percent HW and 2 percent Cargil HemiForce ™ Enhanced Fiber Additive (AFM). The AFM was diluted below 2 percent consistency and allowed to mix in the mixed existence tray for 20 minutes before starting the formation of the paper tissue. The speed of the paper machine (the speed of the Yankee dryer) was 50 feet (1524 cm) per minute (fpm).

Example 2 (Invention) A simple sheet bath paper was made as described in Example 1, except that the pulp blend was 19.8 percent SW, 79.2 percent HW and 1 percent AFM.

Example 3 (Invention) A simple sheet bath paper was made as described in Example 1, except that the pulp mixture was 9.7% SW, 87.3% HW and 3% AFM.

Example 4 (Control 1) A simple sheet bath paper was manufactured as described in Example 1, except that the softwood fibers were not refined and the pulp blend was 40 percent SW, and 60 percent HW. No AFM was added to the pulp mix.

Example 5 (Control 2) A single sheet bath paper was manufactured as described in Example 1, except that the softwood fibers were refined for 9 minutes and the pulp mixture was 40 percent SW, and 60 percent HW. No AFM was added to the pulp mix.

Example 6 (Control 3) A single sheet bathing paper was made as described in Example 1, except that the pulp mixture was 40 percent SW, and 60 percent HW. No AFM was added to the pulp mix.

Example 7 (Control 4) A single sheet bathing paper was made as described in Example 1, except that the pulp mixture was 39.6 percent SW, and 59.4 percent HW and 1 percent AFM.

Examples 8-16. (They trade A number of commercially available toilet paper samples were collected and tested for various properties. The delivery compositions are not known.

All papers were measured for rigid dry basis weight, geometric average tensile strength, dispersibility (turbid water box cycles) and opacity. The invention 1 and the 2 samples and the control samples 3 and 4 were also classified for the softness of the panel. These samples were selected for the softness test since they all had approximately the same geometric mean tensile strength. The paper samples were provided to a trained panel that selected the paper samples for surface smoothness on a relative scale. A classification of "A" was considered relatively softer than a classification of "B". The results are presented below in Table 1.

Table 1 The results show with respect to the softness, that the sample of the invention 2 had the highest surface smoothness (95% confidence level) among the papers tested. The other sample of the proven invention (Invention 1) was judged to have surface smoothness similar to that of the controls. These data indicate that the inventive roles were at least as smooth as the control codes.

The results further show that the papers of this invention have improved dispersibility and better opacity (as measured by the ratio of the opacity divided by the basis weight) to a set geometric fixed tensile strength. Obtaining the desired combination of softness, tensile strength, dispersibility and efficiency of fiber opacity required chemical delivery and handling. As the data in Table 1 indicate, the Control 1 sample had very good dispersibility (1 cycle) for not refining the softwood fibers in the supply. However, the sample also had a very low geometric mean tensile strength of 311 grams. On the other hand, the Control 4 sample, which includes AFM of 1 percent dry weight in the fiber supply, had a good geometric average tensile strength of 597 grams, but a higher dispersibility (1.8 cycles), which was only somewhat better than the best of the commercially available bath papers (2 cycles for the Albertson product). Therefore, to improve the dispersibility, the supply was adjusted for the samples of the inventive to include the fibers of additional hardwood and / or AFM. For the sample of Invention 1, the AFM content of the supply was increased to 2 percent by dry weight. For the samples of Invention 2 and 3, the hardwood portion of the supply was increased to approximately 80 percent and 90 percent, respectively. In all cases, the dispersibility was 1 cycle and the geometric mean tensile strength was above 550 grams.

Without being attached to a theory, it is believed that the increase in the hard mature portion of the supply increased the dispersibility of the product (that is, reduced the number of cycles) and increased the opacity of the product. This is thought to be due to the higher fiber count and the reduced fiber length associated with the replacement of hardwood fiber for a portion of the soft wood fiber. The higher fiber count of the hardwood pulp is thought to have increased opacity and the decreased fiber length is thought to have increased product dispersibility. However, the increase in hardwood fiber content also decreased the product's tensile strength, possibly reducing it below the required strength level. This was counted when necessary by increasing the level of AFM as the AFM that provides the improved strength and efficiency of opacity of the fiber as well as good dispersibility.

It will be appreciated that the foregoing examples, given for purposes of illustration, are not construed as limiting the scope of this invention, which is defined by the following claims and all equivalents thereof.

Claims

1. A soft paper having a rigid dry basis weight of about 15 to about 35 grams per square meter, about 5 to about 40 weight percent of soft wood fibers and about 60 to 95 weight percent dry weight of hardwood fibers, an average geometric tensile strength from about 500 to about 1000 grams by 3 inches wide (7.62 cm) and a dispersibility of about 1.5 cycles or less.

2. The paper according to claim 1, which has a dispersibility of about 0.5 to about 1.5 cycles.

3. The paper according to claim 1, which has a dispersibility of about 0.5 to about 1.0 cycles.

4. The paper according to claim 1, having a dispersibility of about 1 cycle.

5. The paper according to claim 1, which has an opacity ratio divided by the rigid dry basis weight of about 2.5 percent / gsm or greater.

6. The paper according to claim 1, which has an opacity ratio divided by the rigid dry basis weight of about 2.5 percent / gsm to about 3.0 percent / gsm.

7. The paper according to claim 1, having an opacity ratio divided by the rigid dry basis weight of about 2.56 percent / gsm.

8. The paper according to claim 1, consisting of a single sheet.

9. The paper according to claim 1, having from about 10 to about 20 percent dry weight of soft wood fibers and from about 80 to about 90 percent dry weight of hardwood fibers.

10. A soft paper having a rigid dry basis weight from about 15 to about 35 grams per square meter, from about 5 to about 40 percent dry weight of soft wood fibers and from about 60 to about 95 percent dry weight of hardwood fibers and from about 0.5 to about 5 percent dry weight of an Enhanced Fiber Additive, said paper having a geometric average tensile strength of about 500 to about 1000 grams per 3 inches (7.62 cm) in width and a dispersibility of approximately 1.5 cycles or less.

11. The paper according to claim 10, which has from about 0.5 to about 4 percent dry weight of an Enhanced Fiber Additive.

12. The paper according to claim 10, having from about 1 to about 3 percent by dry weight of an Enhanced Fiber Additive.

13. The paper according to claim 10, which has dispersibility from about 0.5 to 1.5 cycles.

14. The paper according to claim 10, having dispersibility of about 1 cycle.

15. The paper according to claim 10, having an opacity ratio divided by the weight of the rigid dry base of about 2.5 percent / gsm or greater.

16. The paper according to claim 10, which has an opacity ratio divided by the weight of the rigid dry base from about 2.5 percent to about 3.0 percent / gsm.

17. The paper according to claim 10, which has an opacity ratio divided by the weight of the rigid dry base from 2.56 to 2.70 percent / gsm.

18. The paper according to claim 10, consisting of a single sheet.

19. The paper according to claim 10, having from about 10 to about 20 percent dry weight of soft wood fibers and from about 80 to about 90 percent dry weight of hardwood fibers.