Paper making and fiber liberation – Apparatus – Digester
Reexamination Certificate
1998-07-30
2001-05-08
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Apparatus
Digester
C162S163000, C162S164400, C162S164700, C162S167000, C162S168100, C510S504000, C510S524000, C510S525000, C510S526000
Reexamination Certificate
active
06228223
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aqueous softening and antistatic agent composition, which is useful for the treatment of cellulosic material, in particular fluff pulp, fluff, and tissue. Said composition comprises a quaternary ammonium compound and an alkoxylated fatty acid or an alkoxylated fatty alcohol. Furthermore the invention also relates to a method for providing cellulosic materials with a reduced tendency to retain an electrostatic charge as well as providing the material with improved softness, wherein the material is treated with said composition.
Softening and antistatic agents are frequently used in the production of fluff and tissue.
EP-A-765,418, for instance, relates to a method for the production of fluff pulp in which an antistatic agent composition comprising quaternary ammonium compounds is used; the composition is however not indicated to have any softening properties.
On the other hand WO 97/04170 discloses a tissue containing a softening composition comprising quaternary ammonium compounds and fatty acid alkoxylate or ethoxylated glycerine or lanolin, which is not indicated to have any antistatic properties.
U.S. Pat. No. 4,476,323, however, discloses a composition which is used in a process for the treatment of cellulosic materials to impart a reduced tendency to retain an electrostatic charge and improved softness and/or reduced mechanical strength due to the reduction in interfiber bonding. The composition contains certain quaternary ammonium compounds which comprises in particular a 2-hydroxy-oxypropylene group, which is believed to provide the combined antistatic and softening properties. Apart from this, the composition may contain nonionic surfactants, such as alkoxylated aliphatic alcohols or acids. There is no suggestion given about the compositions biodegradability.
U.S. Pat. No. 5,312,522 discloses however a biodegradable softening composition used in paper products such as tissue. The composition contains certain quaternary ammonium compounds, namely mono- and diester variations of some common quaternary ammonium salts, which esters are said to be biodegradable, in contrast to the corresponding salts; the esters are also said to function as debonding agents. Optionally, the composition may also contain nonionic surfactants such as alkylpolyethoxylated esters. No indication is given about any antistatic properties of the composition.
It would be—particularly in view of the documents referred to above—desirable to be able to provide a softening and antistatic agent composition useful for the treatment of cellulosic material, which composition is biodegradable. Thus, the problem to be solved by the present invention is to provide such a composition.
SUMMARY OF THE INVENTION
The present invention relates to an aqueous softening and antistatic agent composition, which is useful for the treatment of cellulosic material, in particular fluff pulp, fluff, and tissue. Said composition comprises a quaternary ammonium compound and an alkoxylated fatty acid or an alkoxylated fatty alcohol. Furthermore the invention also relates to a method for providing cellulosic materials with a reduced tendency to retain an electrostatic charge as well as providing the material with improved softness, wherein the material is treated with said composition.
DETAILED DESCRIPTION OF THE INVENTION
In view of what is stated in U.S. Pat. No. 5,312,522 about the biodegradability of common quaternary ammonium salts, the problem has now surprisingly been solved by the claimed invention. In more detail the present composition is an aqueous softening and antistatic agent composition comprising a biodegradable nonionic surfactant and a quaternary ammonium compound having the formula
wherein R
1
is a C
6
-C
22
hydrocarbyl group; and X is halogen or SO
4
2−
, the concentration of the quaternary ammonium compound in the composition being at least about 15% by weight, preferably at least about 20% by weight. The quaternary ammonium compound may, for instance, be chosen among C
12
-C
16
alkyldimethyl-benzylammonium salts and benzylcocoalkyldimethyl-ammonium salts. In a preferred embodiment of the invention the quaternary ammonium compound is a benzyl-cocoalkyldimethyl-ammonium salt. The anion of the salt may be chosen among the halogen ions, particularly the chloride and bromide ions, and the sulphate ion, although in the preferred case it is a chloride ion; the Chemical Abstracts Service Registry Number of this preferred substance is 61789-71-7. The cocoalkyl group comprises even-numbered, aliphatic, straight-chained C
8
-C
18
hydrocarbyl groups. In a preferred embodiment each one of the C
8
-C
18
hydrocarbyl groups in the cocoalkyl group represents at least about 2 mole-%, calculated on the total number of moles of said hydrocarbyl groups chains in said cocoalkyl group. The preferred mole percentage ranges of the hydrocarbyl groups in the cocoalkyl group are indicated in Table I below
TABLE I
HYDROCARBYL GROUP
MOLE PERCENTAGE RANGE
C
8
2-7%
C
10
2-7%
C
12
45-55%
C
14
15-25%
C
16
4-14%
C
18
4-14%
The biodegradable nonionic surfactant is a linear alkoxylated fatty acid or a linear unsaturated alkoxylated fatty alcohol. In the present application “alkoxylated” signifies that the compound is obtainable (although it may be obtained in alternative ways using alternative starting substances) from a reaction between a fatty acid or fatty alcohol and an alkylene oxide, such as for instance—but not restricted to—ethylene oxide or propylene oxide. Preferably, the alkoxylated fatty acid is unsaturated. In a preferred embodiment the alkoxylated unsaturated fatty alcohol is derived from unsaturated C
10
-C
20
alcohols containing one or two double bonds. The unsaturation has a positive impact on the wettability of the treated cellulosic material. In a particularly preferred embodiment the alkoxylated unsaturated fatty alcohol is ethoxylated oleyl cetylalcohol obtainable from an adduction reaction between ethylene oxide and oleyl cetylalcohol in a molar relation of up to about 15 moles of ethylene oxide to about 1 mole of oleyl cetylalcohol, preferably between about 4-6 moles of ethylene oxide to about 1 mole of oleyl cetylalcohol. It is particularly preferred that the surfactant is obtainable from an adduction reaction between 5 ethylene oxide and 1 mole of oleyl cetylalcohol. This preferred surfactant has Chemical Abstracts Service Registry Number 68155-01-1. Again, the term “obtainable” indicates that the ethoxylated oleyl cetylalcohol may be obtained by alternative reaction routes.
Apart from the active substances discussed above the composition may contain various additives, for instance solution viscosity reducing additives such as suitable glycols, e.g. ethylene glycol or propylene glycol, ethanol, or the ethyl ether of diethylene glycol.
As indicated above the present invention also relates to a method for antistatic and softening treatment of cellulosic materials in which the present aqueous softening and antistatic agent composition is used. The cellulosic material may for instance be pulp, such as mechanical pulp (MP), stone groundwood pulp (SGW), pressure groundwood pulp (PGW), refiner mechanical pulp (RMP), thermo-mechanical pulp (TMP), chemi-mechanical pulp (CMP), or chemi-thermomechanical pulp (CTMP). In a preferred embodiment the cellulosic material is fluff pulp, i.e. pulp intended for dry shredding to yield fluff. The cellulosic material may also be fluff or tissue. The present method may be used for the production of a number of cellulosic products the softness of which is of great importance, such as toilet paper, hygienic tissues, tissue paper, paper sheets, paper fabrics, paper towels, paper tablecloths, and paper clothing.
At said treatment the present composition may be added to cellulose material suspended in water, for instance in the stock of a pulp production process prior to the forming of the pulp sheet. The amount of the present composition in the stock is suitably up to about 10 kg/ton of dry pulp, preferab
Ankarbratt Lisbeth
Thebrin Ingemar
Akzo Nobel nv
Halpern Mark
Parker Lainie E.
Silverman Stanley S.
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