The present invention relates to cellulose fiber materials containing 0.01 to 0.5 % by weight of ammonia compound comprising oxyalkyl radicals consisting of at least 3 carbon atoms which are biodegradable at a degree of at least 60% according the OECD 301 F method and a process for producing debonded cellulose fibers.

Debonders are used in the manufacture of fluff pulp, tissue paper and other forms of paper. In tissue paper, paper toweling and other forms of paper, debonders can be used to decrease density of the fiber sheet. Decreasing the density of the sheet can among other things change the absorption properties and printability of different types of paper and tissue. This allows the paper manufacturer to achieve desired end use properties.

There are two main types of chemicals used as debonders for fluff pulp and tissue. The first group of materials are di-alkyl dimethyl ammonium chloride where the alkyl groups are from 8 to 20 carbons long. The second type are materials based on quaternized imidazolines-

US 3,755,220 disclose that certain chemical additives known as debonding agents interfere with the natural fiber-to-fiber bonding that occurs during sheet formation in papermaking processes. This reduction in bonding leads to a softer, or less harsh, sheet of paper. Freimark et al. go on to teach the use of wet strength resins to enhance the wet strength of the sheet in conjunction with the use of debonding agents to off-set undesirable effects of the wet strength resin. These debonding agents do reduce dry tensile strength, but there is also generally a reduction in wet tensile strength.

US 3,821 ,068 also disclose that chembal debonders can be used to reduce the stiffness, and thus enhance the softness, of a tissue paper web.

Chemical debonding agents have been disclosed in various references such as US 3,554,862.

These materials include quaternary ammonium salts such as trimethylcocoammonium chloride, trimethyloleylammonium chloride, di(hydrogenated) tallow dimethyl ammonium chloride and trimethylstearyl ammonium chloride.

US 4,144,122 disclose the use of complex quaternary ammonium compounds such as bis(alkoxy(2- hydroxy )propylene) quaternary ammonium chlorides to soften webs. The authors also attempt to overcome any decrease in absorbency caused by the debonders through the use of nonionic surfactants such as ethylene oxide and propylene oxide adducts of fatty alcohols.

WO 1993/021382 disclose that the use of dimethyl di(hydrogenated) tallow ammonium chloride in combination with fatty acid esters of polyoxyethylene glycols may impart both softness and absorbency to tissue paper webs.

Conventional quaternary ammonium compounds such as the well known dialkyl dimethyl ammonium salts (e.g. ditallow dimethyl ammonium chloride, ditallow dimethyl ammonium methyl sulfate, di(hydrogenated) tallow dimethyl ammonium chloride etc.) are effective chemical debonding agents. Unfortunately, these quaternary ammonium compounds are not biodegradable.

It is an object of the present invention to achieve a debonder which is dispersible at room temperature and which is readily biodegradable.

Surprisingly, the quaternary ammonia compounds of the invention solve at least one problem of the prior art.

The present invention accordingly provides cellulose fiber materials containing 0.01 to 0.5 % by weight of ammonia compounds of formula (I) based on the dry weight of cellulose fiber material

R ₂ N ⁺ ((A)aR ² ) ₂ B- Formel (l)

wherein

R independently an alkyl group consisting of 1 to 6 carbon atoms;

R ² independently an unsaturated or saturated acyl group;

A independently an oxyalkyl radical consisting of at least 3 carbon atoms;

a 1 to 3;

where the radicals R ² consist of 60% to 99% (w/w) of unsaturated acyl groups;

B is an anion selected from consisting of chloride, acetate, methyl sulfate, and mixtures thereof;

where the compounds of the formula (I) are biodegradable at a degree of at least 60% according the OECD 301 F method.

The invention further provides an absorbent material consisting of the debonded cellulose fibers according the invention.

The invention further provides a process for producing the debonded cellulose fibers according the invention.

The invention further provides a method of debonding cellulose fibers using ammonia compounds of the formula (I).

The invention further provides a method of lubricating cellulose fibers using liquid ammonia compounds of the formula (I).

It is advantage that the inventive compounds of the formula (I) are biodegradable. Another advantage is that the inventive compounds are liquid at room temperature.

Especially advantageous is that the compounds of the invention allow a dose dependent change of properties, particularly the absorbance and the burst index. Absorbency is the measure of the ability of a product, and its constituent webs, to absorb quantities of liquid, particularly aqueous solutions or dispersions. Overall absorbency as perceived by the human consumer is generally considered to be a combination of the total quantity of liquid a given mass of tissue paper will absorb at saturation as well as the rate at which the mass absorbs the liquid.

Debonding is the masking of hydrogen bonds between the individual cellulosic fibers. The tissue formed has finally enhanced flexibility and lubrication between the individual fibers and is not stiff and rough.

The subject-matter provided by the invention is illustratively described herein below without any intention to limit the invention to these illustrative embodiments. Where ranges, general formulae or compound classes are specified herein below, these shall include not just the corresponding ranges or groups of compounds that are explicitly mentioned but also all sub-ranges and sub-groups of compounds which can be obtained by extracting individual values (ranges) or compounds. When documents are cited in the context of the present description, the contents thereof, particularly with regard to the subject-matter that forms the context in which the document has been cited, are considered in their entirety to form part of the disclosure content of the present invention. Unless stated otherwise, percentages are figures in per cent by weight. When average values are reported herein below, the values in question are weight averages, unless stated otherwise. When parameters which have been determined by measurement are reported hereinafter, they have been determined at a temperature of 25°C and a pressure of 101 325 Pa, unless stated otherwise.

Preference is given to quaternary ammonia compounds of formula (I) which are liquid at ambient temperature, preferable have a melting point of melting range between - 20°C to +20°C, more preferable between -10 to + 15°C, particularly preferable between 0 to 10°C.

The advantage of liquid quaternary ammonia compounds of formula (I) is that these compounds are able to penetrate deeper into the cellulose fibers, that they remain liquid even on dry products made of the cellulose fibers thus making these products more flexible and soft. A further advantage is that the energy upload of a hammer mill used for subsequent fiberizing a raw cellulose fiber containing product in order to get a fluff pulp is lowered, thus the temperature of the product within the hammering process is lowered.

Preference is given to quaternary ammonia compounds of formula (I) where R ² is preferably independently of one another identical or different acyl radicals of saturated or unsaturated fatty acids.

Prefered fatty acids include 4 up to 40 carbon atoms, more preferably, the fatty acids are unsaturated selected from among palmitoleic acid ((Z)-9-hexadecenoic acid), oleic acid ((Z)-9-hexadecenoic acid), elaidic acid ((E)-9-octadecenoic acid), cis-vaccenic acid ((Z)-1 1- octadecenoic acid), linoleic acid ((9Z.12Z)- 9,12- octadecadienoic acid), alpha-linolenic acid ((9Z,12Z,15Z)-9,12,15-octadecatrienoic acid), gammalinolenic acid ((6Z,9Z,12Z)-6,9,12-octadecatrienoic acid), di-homo-gamma-linolenic acid ((8Z,1 1Z.14Z)- 8,11 ,14-eicosatrienoic acid), arachidonic acid ((5Z,8Z,1 1Z,14Z)-5,8,11 ,14-eicosatetraenoic acid), erucic acid ((Z)-13-docosenoic acid), nervonic acid ((Z)-15-tetracosenoic acid), ricinoleic acid, and undecenoic acid, and mixtures, such as, for example, rapeseed oil acids, soya fatty acids, sunflower fatty acids, peanut fatty acids and tall oil fatty acids. Especially preferred in this context are radicals of oleic acid. More especially preferred are the quaternary ammonia compounds of formula (I) which are liquid, and where the acyl radicals are of fatty acid mixtures comprising oleic acid, stearic acid, palmitic acid and gamma- linolenic acid, where these abovementioned fatty acids preferably amount to at least 85% by weight in the fatty acid mixture.

Especially preferred are the quaternary ammonia compounds according to the invention which are liquid where the acyl radicals of fatty acid mixtures comprise oleic acid at least 70% by weight, preferably at least 75% by weight, more preferably at least 80% by weight, even more preferably at least 85% by weight, particularly preferably at least 90% by weight and especially preferably at least 95% by weight, the sum total of all fatty acids being 100% by weight.

Preference is given to quaternary ammonia compounds of formula (I) wherein R is independently selected from the group of hexyl, pentyl, n-butyl, i-butyl, n-propyl, i-propyl, ethyl and methyl, especially preferably methyl;

A further advantage of the quaternary ammonia compounds according to the invention is their biodegradability.

The biodegradability is preferably determined by the OECD 301 F method. More preferably, the biodegradability is determined as specified in 28 d of OECD 301 F.

The quaternary ammonia compounds according to the invention preferably have a biodegradability of at least 60%, even more preferably of at least 70% and especially preferably of at least 75%, the maximum biodegradability value being 100%.

Preference is given to quaternary ammonia compounds of formula (I) which are miscible with organic solvents, preferably without miscibility gap at ambient temperature, preferable between 0 to 20°C.

Sovents are any non-toxic, non-ecotoxic organic compounds having at least one hydroxyl group, preferably mono hydroxyl aliphatic compounds, di hydroxyl aliphatic compounds, oligo hydroxyl aliphatic compounds which can be oligomeric or polymeric. More preferably the solvents are selected from alcohols, glycols, oligo or poly oxyalkylene compounds, more preferably selected from or poly oxypropylen compounds, further more preferably selected from poly oxyethylene or poly oxypropylen compounds with Mw 200 to 1000 g/mol, particularly those poly oxyalkoxylenes which are terminated on one end with an unsaturated fatty acid as defined above.

Preferably the solvents according the invention are biodegradable wherein biodegradable is understood as before mentioned.

Miscibility in the context of the invention is understood to mean the quaternary ammonia compounds of formula (I) having a solubility of at least 10 g/l, preferably at least 20 g/l, 50 g/l, 100 g/l and especially preferably of at least 150 g/l solvent at a temperature of 20°C. The upper solubility limit is preferably up to and including 900 g/l, more preferably 800 g/l, 700 g/l and especially preferably up to and including 600 g/l solvent at 20°C. Determining the -solubility is comprehensible to the skilled person, who determines it preferably according to Regulation EC 440/2008 Part A.6, more preferably by the flask method of Regulation EC 440/2008 Part A.6.

Preference is given to quaternary ammonia compounds of formula (I) where the fatty acid or fatty acid mixture has iodine number between 105 and 130, preferably between 1 10 and 125.

Iodine numbers [g of iodine/100 g of sample] are determined by the method of Hanus, known as method DGF C-V 1 1 a (53) of the German Society for Fats, and arithmetically converted into the molar masses MWIN for the respective fatty acid or fatty acid mixture.

Preference is given to cellulose fiber materials containing 0.02 to 0.3 % by weight of quaternary ammonia compounds of formula (I) based on the dry weight of cellulose fiber material, wherein

R is independently selected from the group of hexyl, pentyl, n-butyl, i-butyl, n-propyl, i-propyl, ethyl and methyl,, especially preferably methyl;

R ² independently an unsaturated or saturated acyl group where the radicals R ² consist of 60% to 99% (w/w) of unsaturated acyl group and where the unsaturated acyl group consist of at least in 70% of oleic acid; a is 1 ;

A is independently - CH ₂ CH(CH ₃ ) - O - or - CH(CH ₃ ) CH ₂ - O -;

B is MeOSOs-.

More preferred are cellulose fiber materials containing 0.02 to 0.3 % by weight of quaternary ammonia compounds of formula (I) based on the dry weight of cellulose fiber material, wherein

R is methyl

R ² independently an unsaturated or saturated acyl group with a iodine number between 105 and 130, preferably between 1 10 and 125;

a is 1 ;

A is independently - CH ₂ CH(CH ₃ ) - O - or - CH(CH ₃ ) CH ₂ - O -;

B is MeOSOs ^" .

Particularly preference is given to cellulose fiber materials containing 0.03 to 0.2 % of liquid ammonia compounds of formula (I) based on the dry weight of cellulose fiber material, wherein R is Methyl, R ² is oleic acid, a is 1 , A is - CH ₂ CH(CH ₃ ) - O - or - CH(CH ₃ ) CH ₂ - O -, B is MeOSOs ^" ; where the iodine number of R ² is between 1 10 and 130; and where the biodegradability is at least 60% according the OECD 301 F method.

Preference is given to cellulose fiber materials selected from paper, tissue paper, paper toweling or non- woven material made of debonded cellulose fibers. Preference is given to absorbent material with a higher water absorbance as the same material without the use of ammonia compounds of formula (I).

Preference is given to a process for producing debonded cellulose fibers consisting of the steps

(a) optionally dissolving the ammonia compounds of the formula (I) in a solvent

(b) diluting the ammonia compounds of the formula (I) in water

(c) adding the water solution (b) to cellulose fiber materials.

Due to the strong adhesion to the fiber surface ammonia compounds of formula (I) are advantageous because food contamination is prevented,

Another advantage of the ammonia compounds of formula (I) is the low surface tension watery solutions, this causes a good penetration into the cellulose fibers.

The quaternary debonder helps to manufacture in a high speed industrial process generating a tissue weight of < 50 g/m ² , that is mainly used for paper towels or even tissue sheets with a weight of 12-20 g/m ² that is typically used as toilet tissue. Examples

Methods and materials

Table 1 : test compounds, all products are commercially available and trademarks of Evonik, Germany entry tradename melting range [°C]

ex 1 Adogen® 442 60 - 70

ex 2 REWOQUAT V 10036 ZW (Varisoft 3690) 30 - 50

ex 3 REWOQUAT DEEDMAC 55 - 65

ex 4 REWOQUAT CR 3099 5 - 10 °C

REWOQUAT V 10036 ZW is the active ingredient of Varisoft 3690. Preparation or tissue sheets:

Untreated fluff pulp from a Scandinavian mill was obtained from the high density chest. This fluff pulp was used to form hand sheets with a Rapid Kothen hand sheet former as supplied by Frank PTI using ISO 5269- 2. Four hand sheets were made for each experimental condition, including four sheets that were not treated with any debonder. The sheets were then tested for burst index, absorbency, density and softness. The data reported represents the average of each condition. The method for preparing the debonder samples and subsequently treating the fiber used to make hand sheets is as follows.

The pulp received was 7.29% (w/w) consistency in water. The consistency needed for preparation of sheets should be 0.18% by weight. In order to achieve this, the water to pulp ratio was using pulp as supplied in amount of 2.467% and water 97.533% by weight based on the sum of 100% by weight. This was mixed for one hour at 400 rpm with an overhead mixer resulting in a fluff pulp slurry.

The debonders were dissolved in propylene glycol by mixing 40 g of pure debonder in 60 g of propylene glycol. In case of the dialkyldimethyl ammonium chloride (Adogen 442) this compound was melted and then added to warm (T = 50 - 80°C) propylene glycol and held at this temperature until dispersed in water.

These debonder solutions were dispersed in city water using 0.625 g of the above debonder solution in propylene glycol and 99.375 g of city water by mixing this for 90 minutes at 400 rpm resulting in sample A consisting of Adogen 442, sample B consisting of REWOQUAT V 10036 ZW and sample C consisting of the compound according the invention REWOQUAT CR 3099.

To 3 500 imL of the above fluff pulp slurry different amounts of samples A, B and C were added as indicated in table 2. The dose is based on the use of the above debonder solution in kg per dry weight of the pulp in ton. The resulting concentration is weight of pure debonder base on the weight or dry pulp.

table 2: Definition of the attempts

entry Debonder dose; [kg/ton] mL to add Resulting concentration; [%(w/w)]

1 0 0 0

2 1 6.4 0.04

3 3 0.12

4 4 25.6 0.16

The resulting mixtures were stirred for 5 minutes at 500 rpm at room temperature.

The preparation of the hand sheets was performed with a Rapid Kothen Sheet Machine (FRANK-PTI) according to the product sheet number 95854 of company FRANK-PTI with some amendments.

The individual steps were carried out manually via the selector switch. At first water was introduced into the forming column. When it has been filled to the 4 liter mark, 800 ml the suspensions of table 1 were added. When the 7 liter mark was reached, the flow of water was stopped manually and agitation begins under pressure of compressed air. After the agitation was completed, the suspension came to rest for 5 seconds and the draining process started (approximately 20 seconds) by decompression of the suction chamber. The hand sheet was formed on the screen frame.

A carrier board was placed with its smooth side downwards centrally on the wet sheet. Then a couch roll was rolled back and forth over the sheet for a 2-second period without additional pressure, once in each of two directions at right angles to each other. The couch roll had been placed on the edge of the screen but not on the wet sheet. After removing the sheet-forming screen together with the wet sheet and the carrier board from the supporting screen it was hit with the edge slightly inclined to the horizontal against the silicon rubber underlay releasing the board to which the wet sheet was attached on the underlay.

After placing the round metal plate onto the center of the wet sheet the sheet was peeled from the carrier board and air dried. The hand sheets were further prepared for the tests by storing under controlled climate (72°F, 50% relative humidity) until constant weight.

Properties of the tissue sheets:

Burst testing is performed on the Vantage Tensile Tester (Thwing-Albert Instrument Company, USA) utilizing the Tissue Burst attachment. The lower the burst index, the weaker the test sample, which equates to better debonding.

The sheets were test for water absorbency on a M/K Systems model 251 GATS (Gravimetric Absorption Testing System) instrument which tests Horizontal wicking. This instrument determines rate of absorption and capacity of the test substrate by placing a sample of known weight on a porous plate attached to an instrument and analytical balance. The porous plate is attached to a water reservoir placed on an analytical balance. The instrument measures the rate of absorption and capacity by measuring the quantity and speed of water leaving the reservoir that supplies the porous plate.

The density of the sheets were measured with a Messmer micrometer Model 172M.

The sheets were analyzed for softness using a TSA (Tissue Softness Analyzer) supplied by Emtec Electronic GmbH, Germany. The tissue softness values are expressed as "hand feel". A two point increase in hand feel is considered significant and can be perceived by the average human.

Table 3: results of the property determination

Entry sample Burst index; Density; Absorption Rate; Hand Feel ref table 2 [Pa*m ² /g] [mg/mL] [g/sec]

0 - 31.7 249.27 2.031 63

1 A 27.7 243.27 1.563 64

1 B 28.8 245.02 1.774 64

1 C 30.2 244.71 2.216 62

2 A 20.3 240.91 1.105 65

2 B 15.5 246.54 1.328 69

2 C 15.5 243.52 1.490 67

3 A 17.9 246.98 1.034 66

3 B 12.8 249.01 1.492 70

3 C 12.7 241.11 1.355 72

The results show the advantage of the compounds of the invention. The burst index is effectively lowered and not only better than the blank but at higher concentrations also better than the compounds of the art. The density is comparable to those of the art but clearly effectively lowered at high concentrations. The absorption rate is being modified in a wide range.

Table 4: certain eco toxicological data according different OECD methods

method (OECD) Adogen 442 V 10036 CR 3099 DEEDMAC

Fish; aqua tox 10.1 1.8 >10 5.2

(203); 96h; LC50 [mg/Lj

Aquatoxicity, invertebrates, Daphnia magna; 0.19 0.105 >8.8 14.8

(202)48 h; EC50 [mg/L]

Biodegration 3% (A) 13% (B) >60% (F) >60% (B) (301 *)