The present invention concerns cellulosic fibres with hydrophobic properties.

Cellulosic man-made fibres are known for their hydrophilic, water absorbing attributes. In contrast synthetic fibres such as polyester, polyethylene and polypropylene are inherently hydrophobic which means that they do not absorb water into their interior structure.

Some natural grown fibres like cotton possess natural waxes which protect the plants in nature and make the raw fibre hydrophobic. Usually these waxes are removed to achieve an absorbent, soft cotton fibre for textile and nonwoven processing.

Cellulosic fibres of the viscose type and modal type are produced according to the viscose process. Such fibres have been given the generic names, Viscose and Modal by BISFA (The International Bureau for the Standardisation of man made Fibres)

In recent years the "amine-oxide-process" or "Lyocell process" has been established as an alternative to the viscose process, wherein cellulose, without forming a derivative, is dissolved in an organic solvent of an amine-oxide, in particular N-Methylmorpholine-N-oxide (NMMO). Cellulosic fibres produced from such solutions are called "solvent-spun" fibres and have been given the generic name Lyocell by BISFA (The International Bureau for the Standardisation of man made Fibres).

Other man-made cellulose fibres can be made using chemical processes (e.g. the cuproammonium process) or using other direct solvents such as ionic liquids.

The object of the invention is to provide hydrophobic cellulose fibres which are able to soak and store oil but repel water and are compostable.

Said object is achieved by means of a cellulosic man-made-fibre having hydrophobic properties comprising a hydrophobic agent, characterised in that the fibre has an holding capacity for non polar substances of equal or greater than 10 g substance / g fibre.

In the context of the invention the term "non polar substances" refers to oils comprising alkyl and allyl chains with 8 to 40 carbon or blends of non-polar liquids comprising substances with functional groups, like alcohols, aldehydes, ketones, organic acids, esters and ethers. As hydrophobising agents Alkyl or Alkenyl Ketene Dimer (AKD) is used, which is shown in formula (1 ) , where R1 and R2 are hydrocarbon groups with between 8 and 40 carbon atoms and which can be both, saturated or unsaturated, straight- chained or branched.

(1 ) R1 -CH =C-CH— R2

K I I

O— C=0

Formulations which have similar effects are substituted cyclic dicarboxylic acid anhydrides like substituted succinic or glutaric acid anhydrides and similar.

The preferred Alkyl Ketene Dimers are prepared from acid chlorides by e.g. the method described by R. Adams, Org. Reactions Vol. Ill, p 129 John Wiley & Sons Inc. NY 1946 or J.C. Saner; Journal of the American Chemical Society, Vol. 69, p. 2444 (1947).

Alkyl Ketene Dimer (AKD) is well known in the paper industry to enhance the water repellence of surfaces e.g. used in food packaging. The use of AKD is known for sizing papers as known from GB 2 252 984 A and EP 0 228 576 B1. The joint use of AKD and ASA (alkyl succinic acid) is described in W099/37859. AKD is usually used at the wet end of the paper machine.

AKD formulations are commercially available for example Hydrores© compounds sold by Kemira OYI, Finland. Mostly common are formulations with around 5 - 25% of active compound. Formulation A is an acidic solution with around 1 1 - 12% active compound while Formulation B is an acidic emulsion with an active compound of around 21 - 22% AKD.

In a process for producing a cellulosic fibre with hydrophobic properties the process is characterised by the steps

a) providing a cellulosic fibre with a non-modified surface

b) treating the cellulosic fibre with a hydrophobic agent

The hydrophobic agent can be applied during man made fibre production - this means after the fibre is already formed and washed but before drying, i.e: never-dried fibres. In this case the surface is non-modified.

If commercial available cellulosic fibres, comprising a finish, are used, this finish has to be removed. The cellulosic fibre are preferably treated with the AKD formulation in a concentration range of 0.0001 to 10 % preferably of 0.001 to 5 %, most preferred of 0.001 to 3 % based on cellulosic fibre.

The cellulosic man-made fibres can also

a) be physically modified for example, in shape (trilobal, multilobal) or length (flock, short cut to continuous filament)

b) have incorporated materials , such as colour pigments, flame retardants, ion

exchange resins, carbon blacks.

be chemically modified, for example as is the case with Modal or cross linked fibres.

The invention is shown by the following examples General procedure

All trials were made with Lenzing Viscose 1.3/38 bright, Lenzing Tencel 1.3/38 bright and bleached Cotton. As hydrophobic agent an AKD-formulation like Hydrores ® (Kemira) is used. The commercial available formulations where diluted with water to get the

concentrations shown in the examples.

Viscose:

Example A:

7g bone dry viscose fibres, where the soft finish has been removed with alcohol, are soaked into 100ml of an aqueous Hydrores© solution containing 1% AKD (calc. on cellulose = 0.07g) at room temperature ( approximate liquor ratio 1 :15). After 30 min stirring, the fibres were centrifuged to a moisture content of 50% and dried at 70°C in a desiccators' cabinet to a moisture content of ~ 6%. These fibres are water repellent and soft.

Example B (sample Nr 2):

14g never dried viscose fibres taken wet from the viscose process before after treatment, pressed of to a moisture content of 50% were put into a basin containing an aqueous solution of Hydrores© containing 1% AKD (calc. on cellulose = 0.07g ) at room temperature (liquor ratio 1 :15 again, fibre water retained to be considered). After 30 min stirring, fibres were centrifuged (50% moisture content) and dried at 70 °C in a desiccators' cabinet (both 6% remaining humidity and total dryness). These fibres are water repellent and soft.

Tencel:

Example C: 7g bone dry Tencel fibres where the soft finish has been removed with alcohol, were soaked into an 100 ml aqueous solution of Hydrores© containing 1 % AKD (cafe, on cellulose = 0.07g) at room temperature (liquor ratio approximately 1 :15). After 30 min stirring, fibres were centrifuged (50% moisture content) and dried at 70 °C in a desiccators' cabinet. These fibres are soft and show hydrophobic characteristics.

Example D (sample Nr. 6):

14g Lyocell fibres (containing 50% moisture) taken from the Lyocell process before after treatment, were soaked into an 100ml aqueous solution of Hydrores© containing 1% AKD (calc. on cellulose = 0.07g) at room temperature (liquor ratio 1.15 again, fibre water retained to be considered). After 30 min stirring, fibres were centrifuged to 50% moisture content again and dried at 70°C in a desiccators' cabinet (both 6% remaining fibre moisture and total dryness). These fibres are soft and show hydrophobic attributes. Table 1 shows an overview of the fibre samples and the example numbers.

Table 1 : Overview Fibre samples plus Example Number:

A test method according to European Pharmacopeia (2002) has been established. The only - but significant - change was using peanut oil instead of distilled water.

A little basket made from 0.4mm steel wire (weight: 2.7 ± 0.3g; height: 80mm; mesh size 15 - 20mm) is filled with 3g fibre. A crystallizing dish (diameter 19cm; height: 9cm) is filled 7cm high with peanut oil (olio fritto extra, food grade, bought from the company Olio Spezial Speisefett und Speiseol GmbH, A - 4624 Pennewang/ Wels, Austria; www.olio.at). The basket is hold 10mm (± 3mm) horizontal over the surface and dropped. At this moment the time is taken. After the basket is sunk to the ground it is taken out with a small spoon and allowed to drip for 30 sec. The (reweighed) basket plus fibres were put on a scale to measure the amount of oil held back from fibre. Repeat for 3 times and calculate the mean value. This amount is 3- 4 times increased when measuring fibres with AKD treatment.

The values stay in these areas even after washing the fibres with detergent at 40°C (table 2).

Table 2: Oil uptake of Fibre samples

The examples show that a treated fibre has an oil-uptake which is at least 2 times higher than the oil-uptake of an untreated fibre of the same type. The term "same type" means a fibre of the same nature, titer and length.

Sinking time in water and water retention:

A regular Viscose or Tencel fibre soaks up water and has a sinking time of less than 10 seconds, usually lower than 3 seconds. Fibres hydrophobised with AKD swim on water.

Nonwoven production for further tests:

To determine the contact angle, webs had to be formed:

For this issue both, never dried Viscose and Lyocell fibres were prepared with hydrophobic treatment:

Viscose 1.7/40 dull with 0.5% AKD (example B)

Lyocell 1.7/38 dull with 0.5% AKD (example D)

(As described in Examples B and D with lower AKD concentration) and commercially available Viscose (1.7/40 dull, NW finish) and Lyoceil (1.7/38 dull, NW finish) fibres were produced on a needle punch pilot line from TEC TEX Italy (TECHNO Plants) (Technologies for nonwoven) situated in LAG.

The webs have around 60 gsm (= grams per square meter) or 20 gsm. The used needles were from Groz Beckert and have a length of 3 inches. The webs were 100% hydrophobic fibres or reference fibres, needled from both sides in a range from 00 to 200 (different parameter settings). The needle depth was between 16 and 18 mm. The webs were very uniform and soft. Table 3 shows an overview of the needle punch samples. Table 3: Overview Needle Punch samples

Spunlace Samples:

Fibres achieved according to sample B and D (but with 0.5% AKD instead of 1 %) were sent to a spun lace pilot plant (from University of Leeds) and processed to form webs with around 55 - 60 gsm. This time also blends with commercially available Viscose and Tencel have been made. Table 4 shows an overview of the spunlace samples.

Table 4: Overview Spunlace samples:

Contact angle:

The contact angle is the angle which is formed between a liquid drop and the fibre surface. Contact Angle has been measured using Kruss Equipment and DSA Drop Shape Analysis Software. A single water drop is laid on a nonwoven surface by using the automated dosage system, which controls amount and height of the droplet fall. A picture is taken and the angle between surface and drop is calculated. A number higher than 90° shows that the fabric is hydrophobic. A short video sequence can be taken and so the drop sinking time can be calculated. The greater the contact angle, the worse the ability of wetting. Table 5 shows the results for the needle punched samples and table 6 shows the results for the spunlace samples. A nonwoven according to the invention is characterised in that the contact angle between a nonwoven web comprising only these fibres with water is higher than 1 10°. Table 5: Contact Angle needle punched samples:

Table 6: Contact Angle Spunlace samples:

Polyester is in the range of >120°.

Compostability:

The biodegradability was tested according to ASTM D 6400 (or DIN EN ISO 14855 or DIN EN 14046). Additionally, a test was conducted where fibre webs like described above (samples 10,12,14 and 16) were cut in pieces of around 3x 4cm, the weight was taken and then they were buried in soil (double testing). Samples were taken out after 2 weeks, 1 month and 2 months. The webs are completely composted after that time as shown in table Table 7: Compostability - weight reduction

In case of oil spill the barrier material can be in nature until it disintegrates and composts after the oil has dissipated.

The fibre can also be processed with all state of the art nonwoven techniques e.g. needle punch, spun lace or air laid in both, single use or blends (state of the art). The Textile process chain is also possible.

The inventive fibre can be used in different applications, for example in

oil barrier on land or water, filtration media, especially for oil or grease particles in air, dust wipes, food wrapping, geo textiles or agricultural textiles.