Paper making and fiber liberation – Processes and products – Non-uniform – irregular or configured web or sheet
Reexamination Certificate
1999-10-20
2001-06-12
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-uniform, irregular or configured web or sheet
C162S158000, C162S111000, C162S179000, C162S183000
Reexamination Certificate
active
06245197
ABSTRACT:
This invention relates to paper products in general (e.g., paper towels, facial tissues napkins and sanitary (toilet) tissues), and more particularly, to tissue paper products which have been prepared using an ion-paired softener. The invention also relates to processes used for the manufacture of such tissue papers.
BACKGROUND OF THE INVENTION
For some time paper makers have sought ways to make tissue papers which are soft, yet have sufficient strength.
U.S. Pat. No. 3,556,931 describes treating a sheet of paper with a quaternary ammonium salt debonding agent to soften the sheet. The debonding agent is sprayed on the sheet prior to passing the sheet through a drier.
U.S. Pat. Nos. 4,351,699 and 4,441,962 describe the addition of a quaternary ammonium compound, and at least one specified nonionic surfactant into an aqueous papermaking furnish for making soft, absorbent products such as paper towels. The addition of only quaternary ammonium debonding agents is said to enhance softness, but will also decrease absorbency. The nonionic surfactants are added to overcome the problem of reduced absorbency.
U.S. Pat. No. 4,940,513 describes treating tissue paper with a noncationic surfactant to impart softness. The noncationic surfactants are said to include anionic, nonionic, ampholytic and zwitterionic surfactants. The noncationic surfactants are preferably sprayed on the wet tissue web as it courses through the papermaking machine.
U.S. Pat. Nos. 5,217,576; 5,223,096; 5,240,562; 5,262,007; and 5,279,767 describe the use of quaternary ammonium compound debonding agents for softening tissue paper. Anionic surfactants are described as optional ingredients which can be added to the papermaking furnish so long as they do not significantly and adversely affect the softening, absorbency, and wet strength enhancing actions of the required chemicals.
U.S. Pat. No. 5,494,731 describes tissue papers which have been treated with certain nonionic softeners. The background portion of this document describes certain disadvantages of using cationic debonding agents.
There are numerous problems we have observed with available tissue papers. For example, softness and strength are two important attributes of tissue and towel products. Typically, however, one of those attributes is enhanced at the expense of the other.
One effective technique for enhancing the softness of tissue and towel products is the addition of cationic softeners or debonders to the fiber furnish from which the tissue or towel is made at the wet end of the papermaking system. Unfortunately, the addition of cationic debonders to fiber furnish at the wet end often results in significant reduction of tensile strength (e.g., 15-50% depending on amount added and point of addition). Usually, the furnish, to which debonders are added, is then subjected to refining or the addition of dry strength additives to negate the strength reduction that occurs because of debonder addition. Such treatments, however, often negate the softness benefits imparted by debonder addition. Depending on the type of debonders added, the absorbency rate of the tissue and towel products can also be decreased because of the hydrophobic groups associated with the various debonder formulations.
Cationic debonders, because of their positive charge, are retained on the fiber. On the other hand, anionic softeners and surfactants, because they have the same charge as the fiber, are not sufficiently retained on fiber when they are added to the wet end of the papermaking process. As such, they typically do not function effectively as softeners. They do, however, contribute to wet-end deposition and significant foaming that is detrimental to paper machine operation.
Accordingly, it is an object of the invention to provide a tissue paper product of improved softness, strength and absorbency. It is also an object to provide a manufacturing process for such a tissue paper product where the generation of foam is reduced, or eliminated altogether.
SUMMARY OF THE INVENTION
We have addressed the aforementioned problems through the discovery and development of a softener additive that can enhance softness with minimal strength loss, that will not retard absorbency; and that will not foam significantly when incorporated with the furnish at the wet end of the papermaking system.
We have discovered what we call an ion-paired softener system. The invention, therefore relates to a tissue paper softener system comprising an ion-paired mixture of an anionic surfactant and a cationic amphiphilic compound, wherein the softener system is formulated such that the charge density of the anionic surfactant/cationic amphiphilic compound mixture will be about neutral.
In another embodiment there is provided a process for making a soft, absorbent tissue paper web comprising the steps of forming an aqueous papermaking furnish, depositing the furnish on a foraminous surface, and removing the water from the furnish. An ion-paired softener system according to the invention is added to the furnish or web.
REFERENCES:
patent: 3556931 (1971-01-01), Champaigne
patent: 3998690 (1976-12-01), Lyness
patent: 4351699 (1982-09-01), Osborn, III
patent: 4441962 (1984-04-01), Osborn, III
patent: 4940513 (1990-07-01), Spendel
patent: 5217576 (1993-06-01), Van Phan
patent: 5223096 (1993-06-01), Phan et al.
patent: 5240562 (1993-08-01), Phan et al.
patent: 5262007 (1993-11-01), Phan et al.
patent: 5279767 (1994-01-01), Phan et al.
patent: 5494731 (1996-02-01), Fereshtehkhou et al.
1996 Annual Book of ASTM Standards, pp. 108-111.
Ullman's Encyclopedia of Industrial Chemistry, 5thEdition, pp. 747, 752-756 (1994).
Hughes et al., “Radiotracer and Celloidal Study of Fabric Softer Action”, Text. Chem. Color, vol. 10, No. 5 (1978).
Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, vol. 23, pp. 488-491 (1997).
Awofeso Anthony O.
Kokko Bruce J.
Luu Nga Thuy
Oriaran T. Philips
Schroeder Gary L.
Fort James Corporation
Halpern Mark
Nixon & Peabody LLP
Silverman Stanley S.
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