Patent Description:
Fibrous nonwoven webs are employed in a wide variety of technical fields, from flushable toilet paper and baby wipes to industrial wipes. These nonwoven fabrics often employ pulps as well as viscose fibers. If a higher mechanical strength is required thermoplastic binders, which may be in powder or fibrous shape as well as reinforcing fibers are employed as it is considered as impossible to ensure the required strength without using these components.

<CIT> discloses a nonwoven fibrous web, comprising cellulosic fibers as well as pulp fibers, typically in a weight ratio of (<NUM> to <NUM>):(<NUM> to <NUM>). The web is designed to be employed as flushable toilet paper, i.e. the web is intended to be disintegrated in water under mild agitation conditions. The cellulosic fibers are rayon fibers having a titer of from <NUM> to <NUM>. The pulp is not specified any further. <CIT> discloses a water decomposable nonwoven fabric including first and second regenerated cellulosic fibers and a natural fiber. These different fibers are characterized by means of their fiber lengths and the natural fiber preferably is a pulp fiber. If an increase of mechanical properties is desired, <CIT> emphasizes the importance of employing binder resins. <CIT> discloses a water disintegrable fiber sheet, comprising two different types of pulp, a fibrillated cellulose and a regenerated cellulose fiber. These sheets are intended to be used as simple wipes for one time use and are designed to disintegrate mild agitation conditions, such as the flushing of a toilet, so that they can be easily disposed after use. <CIT> discloses a fibrous nonwoven web material comprising manmade cellulose fibers, natural cellulose fibers and synthetic binder fibers. Again the web is intended to be disintegrated by mild agitation conditions, such as the flushing of a toilet, so that the wipes produced from this web can be easily disposed after use.

These prior art approaches, while providing serviceable wipes, often suffer from the drawback that at least three different fiber materials are to be employed, or that synthetic binder materials, such as synthetic fibers are required to provided sufficient mechanical strength. The use of such synthetic fibers has a detrimental effect on the sustainability of the product, as for example petroleum based materials are used as binder materials. In addition, the use of synthetic binder materials has a negative effect on biodegradability, as for example not all components of the web are decomposed in a suitable time frame and additional filtration and/or purification steps are required in waste water treatment plants (for example for flushable toilet papers or baby wipes comprising such materials). <CIT> discloses a flushable moist wipe or hygiene tissue. This tissue is a nonwoven material containing pulp fibrous and man-made fibres and\or natural fibres. <CIT> discloses a method for production of a hydro-entangled air laid web and products obtained therefrom. The products include natural cellulose fibers by the as well as stable fibers. <CIT>discloses a flushable moist wipe or hygiene tissue and a method for making it. The tissue comprises pulp fibres as well as poly lactic acid fibres the <CIT>discloses a disposable nonwoven web having at least <NUM> layers. <CIT> discloses disposable nonwoven fabrics comprising pulp and solvent spun cellulosic fibres. <CIT> relates to a dispersible non-woven fabric, a method for producing a dispersible non-woven fabric and a wipe or tissue.

Several types of wipes based on cellulosic fibers are already commercially available. The possible uses extend from baby wipes and moist toilet paper (i.e. low mechanical strength webs typically comprising pulp and viscose fibers) to industrial wipes (i.e. high mechanical strength webs which comprise binder fiber and/or reinforcing fibers, typically synthetic fibers such as olefin based fiber or PET fibers). Commercially available industrial wipes do show basis weights in the range of from <NUM> to <NUM>/m<NUM>, with tensile strength properties (machine direction, MD) in the range of from <NUM> to <NUM> N/<NUM> (dry and wet, with the wet tensile strength being somewhat lower). For the wipes with less demands for mechanical properties the respective measures are in the range of from <NUM> to <NUM>/m<NUM> and from <NUM> to <NUM> N/<NUM>. With such webs water retention values (WRV) and liquid absorption capacities (LAC) of from <NUM> to <NUM>% and from <NUM> to <NUM> %, respectively, can be achieved. It is however interesting to note that even the low strength webs, used as baby wipes, do employ synthetic fibers, such as polyester fibers, polyolefin fibers etc. so that even those products for which rather low or intermediate levels of mechanical strength properties are required, are not <NUM>% based on materials produced from renewable sources and introduce synthetic non-biodegradable materials into the waste treatment systems. It therefore seems that the market demands in relation with mechanical properties so far cannot be answered by webs bases exclusively on cellulosic materials.

However, as with the wipes disclosed in the above discussed prior art documents, also the commercially available wipes do suffer from drawbacks, such as the requirement that petroleum based fibers, such as polyolefin fibers or polyester fibers, are essential to achieve high mechanical strength levels, or the use of cellulosic fibers which require a specific fibrillation treatment or are based on regenerated cellulose fibers requiring the use of chemicals which cannot be reused.

It would therefore be preferably if a fibrous nonwoven web material would be available, which ensures high mechanical strength levels without requiring the use of synthetic binder or reinforcing fibers. At the same time it would be advantageous if such a web material could be provided requiring only a minimal number of fibrous materials while still enabling the preparation of a nonwoven web or fabric suitable as wipe in a wide variety of applications. It also would be advantageous if such as web would require only the presence of decomposable fibers, preferably fibers which do not require any post fiber productions treatments, such as chemical fibrillation treatments, and if the fibers to be employed are either natural fibers or regenerated fibers which can be produced in an efficient as well as environmentally friendly way, for example in a manner enabling a vast degree of re-use of any chemicals required for the regeneration process.

The present invention achieves this goal with the fibrous hydroentangled nonwoven web as defined in claims <NUM> to <NUM>, as well as with the process as defined in claims <NUM> to <NUM>. Further embodiments and illustrations of the present invention are outlined in the following.

As outlined in claim <NUM>, one essential component of the web of the present invention is a pulp. This pulp may be of any origin, as long as the requirements as outlined in claim <NUM> are met, namely, the pulp material has a fiber length (LWL, mm) of from <NUM> to <NUM>, a fiber coarseness (mg/<NUM>) of from <NUM> to <NUM> and a fines content (LWL (%)) of from <NUM> to <NUM>. Such a pulp is commercially available at low costs and contributes to the overall commercial feasibility of the fibrous web of the present invention. In particular the fiber length may be of from <NUM> to <NUM>. The pulp may be a bleached or unbleached pulp. In embodiments the pulp may have a coarseness of from <NUM> to <NUM>.

As also outlined in claim <NUM>, a second essential component of the web of the present invention is a lyocell fiber having a length of from <NUM> to <NUM>. Preferably the length is from <NUM> to <NUM>, and in particular from <NUM> to <NUM>, such as from <NUM> to <NUM>. The lyocell fiber may be a standard fiber, a fiber containing a matting agent, a fibrillated fiber etc. As long as the fiber has a length as indicated above, the type of the lyocell fiber has no relevant influence on the essential product properties discussed further below. Preferably, the lyocell fiber has a titer in the range of from <NUM> to <NUM> dtex, more preferably from <NUM> to <NUM> dtex, most preferably from <NUM> to <NUM> dtex, such as <NUM> or <NUM> dtex. A particular suitable lyocell fiber has a fiber length of from <NUM> to <NUM> and a titer of from <NUM> to <NUM> dtex. Such fibers are commercially available, for example under the tradename LENZING™ Lyocell Shortcut from the company Lenzing AG.

These two fiber types, i.e. pulp and lyocell fiber, are the only fibrous components present in the web according to the present invention. Preferably, these two fiber components amount to <NUM> wt. -% or more, more preferably <NUM> wt. -% or more, even more preferably <NUM> wt. -% or more of the web (based on the dry weight of the web). In Embodiments of the present invention, the fibrous nonwoven web according to the present invention contains only pulp and lyocell fibers, and any unavoidable processing additives. preferred if the product in accordance with the present invention is a single layer product, as it is possible to obtain the desired mechanical properties even though using a high proportion of pulp fibres having a small fibre length without requiring the presence of additional layers which in the prior art sometimes are employed in order to strengthen the tissue or wipe product.

The weight ratio of pulp to lyocell fiber is as defined in claim <NUM>, namely the weight ratio is from <NUM>:<NUM> to <NUM>:<NUM>, more preferably from <NUM>:<NUM> to <NUM>:<NUM>. Particularly suitable weight ratios are in the range of from <NUM>:<NUM> to <NUM>:<NUM>, in embodiments <NUM>:<NUM>. However, in particular when the weight of the pulp amounts to at least <NUM>%, the mixtures of pulp and lyocell enable the preparation of webs with the desired balance of properties, while maintaining cost effectiveness.

As will be later explained in greater detail in the context of the process for preparing the web of the present invention, pulp and lyocell fibers are mixed thoroughly prior to the preparation of the web, to ensure a uniform admixture and uniform web properties. Such a mixing typically involves mixing in an aqueous medium, preferably in water. Suitable mixing devices and mixing parameters (agitation, shear rate, amount of fibers in the aqueous medium) are known to the skilled person.

The fibrous nonwoven web in accordance with the present invention has a basis weight in the range of from <NUM> to <NUM> gsm, such as from <NUM> to <NUM> gsm, preferably from <NUM> to <NUM> gsm. Such basis weights are usual in the field of fibrous webs employed for wipes, but the webs in accordance with the present invention do provide a unique combination of mechanical properties at these basis weights, without requiring the presence of synthetic reinforcing fibers or synthetic binders for high mechanical strength levels, or without requiring the use of mixtures of three or even more types of fibers, for lower mechanical strength levels.

As will be explained further in relation with the process of the present invention, it is possible, simply by adjusting the weight ratio between pulp and lyocell fibers and, to a lesser extend also by adjusting optionally the fiber lengths, to tailor the final mechanical properties of the resulting web by means of the energy consumption (i.e. energetic impact on the web materials during hydroentangling the fibers) during hydroentangling, to produce either webs with a lower mechanical strength level (lower energy consumption) or with a higher strength level (higher energy consumption), which typically in the prior art are only achievable by means of employing synthetic reinforcing fibers or binders (in powder of fiber shape). Higher strength levels in accordance with the present invention are strength levels represented by tensile strength (MD, dry, N/<NUM>) of more than <NUM> and in embodiments up to <NUM> or more. In comparison to the commercial high strength wipes, which do show a tensile strength of form about <NUM> up to <NUM> (MD, dry, N/<NUM>), the strength levels achieved by the present invention must be considered as extremely surprising, as all the high strength level materials know in the prior art, for similar but still lower strength levels, require the use of reinforcing and/or binder fibers, such as polyolefin or polyester fibers. It was be no means foreseeable that the rather simple fiber mixture in accordance with the present invention as explained and illustrated above, which doe not even require the presence of reinforcing or binder fibers, enables the provisions of nonwoven materials with at least equal, but in embodiments even higher strength levels.

Accordingly, the present invention provides a fibrous nonwoven web, which is based in fiber materials which are biodegradable and which are furthermore based on natural, i.e. renewable/sustainable raw materials. The use of petrochemical based materials is not required in accordance with the present invention and the lyocell fiber employed in the present invention is produced by a process which reuses to a great extend all chemicals employed, in particular the solvent required for dissolution and spinning, so that an overall green and sustainable product is provided by the present invention. As the starting materials pulp and lyocell fiber to be employed in the present invention are standard materials, the overall costs of the novel product can be maintained on a highly competitive level. Due to the possibility to tailor product properties by means of raw material composition and energy consumption during hydroentangling, it is possible to produce products specifically adapted to the intended end use, so that the present invention may be regarded as providing a module based system which, using only a small number of variables (see above) enables the production of a wide variety of products, without requiring the use of additional components, such as reinforcing fibers, agents to improve biodegradability etc. These advantages associated with the present invention have to be considered as a vast and unexpected improvement over the prior art.

As already outlined in the claims, it is possible to provide the fibrous nonwoven web in accordance with the present invention with two- or three-dimensional structures, for example by embossing, by providing perforations etc., using methods known to the skilled person in the field of fibrous nonwoven webs. The webs in accordance with the present invention allow the provision of such structures without detrimental effect on the mechanical properties (strength) of the webs. It has been found, as illustrated in the examples, that the provision of such structures improves other properties, such as oil uptake, so that high strength webs on accordance with the present invention do show promise in the field of industrial wipes, where so far only reinforced wipes have shown sufficient mechanical strength to allow the use in practice.

The webs in accordance with the present invention in any case do show very good balance of properties, in particular a good balance of mechanical properties (tensile strength) as well as properties relevant for the use, such as WRV and LAC. Webs in accordance with the present invention do show satisfactory LAC values of clearly above <NUM>, in embodiments exceeding <NUM>, typically in combination with WRV of above <NUM>. This is a balance of use properties roughly equivalent to commercial wipes. Tensile strength values for these webs in accordance with the present invention however are typically higher than the values for the commercial wipes, as these typically show tensile strength values (for baby wipes and moist toilet paper) of up to <NUM> N/<NUM> (dry, MD) for low strength products and values of up to <NUM> N/<NUM> (dry, MD) for medium strength products. The corresponding values for the webs of the present invention are up to <NUM> N/<NUM> (dry, MD) for low strength products and values of up to <NUM> N/<NUM> (dry, MD) for medium strength products. Accordingly, the present invention enables, simply be employing two standard products (pulp and lyocell fiber) in the defined weight ratios, the provision of fibrous nonwoven webs with an overall improved balance of use (WRV, LAC) and mechanical (tensile strength) properties. This becomes even more pronounced when considering the high strength webs in accordance with the present invention. These again do show use properties similar to the commercial products, such as WRV and LAC, while achieving the required mechanical properties, in particular tensile strength values without requiring the addition of bonder and/or reinforcing fibers. Commercial industrial wipes, which are a prominent example of high strength webs in this filed, have tensile strength values of from <NUM> up to about <NUM> N/<NUM> (dry, MD), whereas the present invention achieves, without using reinforcing fibers or binder fibers, values (dry, MD of up to <NUM> N/<NUM>. This is a fully unexpected vast achievement over the prior art.

As indicated above, the present invention enables to tailor properties simply by adjusting the weight ratio of pulp to lyocell fiber as well as by adjusting the energy consumption during hydroentangling. Generally, higher contents of lyocell fibers increase mechanical properties. At the same time, increasing the energy consumption during hydroentangling, even for webs comprising a lower proportion of lyocell fibers, has the same effect. Accordingly, high strength webs in accordance with the present invention typically are webs with a higher basis weight, typically of <NUM> or more, with a weight ratio of pulp to lyocell fiber of from <NUM>:<NUM> to <NUM>:<NUM>. Webs with lower basis weights and weight ratios of pulp to lyocell fiber of from <NUM>:<NUM> to <NUM>:<NUM> typically are medium or low strength webs.

As indicated above, the use in particular of the lyocell fibers ensures that in combination with the pulp highly cost efficient webs can be provided which can be considered sustainable. However, the use of the lyocell fibers also unexpectedly serves to increase the mechanical properties, in particular the tensile strength properties of the webs in accordance with the present invention. Unexpectedly the inventors have discovered that only the use of lyocell fibers, as for example compared to other regenerated cellulose fibers, such as viscose fibers, ensures the good mechanical properties. Webs produced with viscose fibers instead of lyocell fibers (with the same length and titer) does not enable the production of webs having strength levels achieved with the corresponding webs employing lyocell fibers (under identical production conditions and using otherwise identical mixtures with pulp). Therefore it is evident, that the present invention is based on a specific selection of raw materials, which males the achievement shown possible.

The present invention will now be described in relation to the process for preparing the fibrous nonwoven webs in accordance with the present invention. It is to be understood that all embodiments as preferences describe above in relation with the webs of the present invention likewise apply to the process disclosed herein. The fibrous nonwoven web in accordance with the present invention may be produced using a hydroentangling process. Such processes are known to the skilled person and conventional devices used for such processes may be use to prepare the webs of the present invention.

Typically, the process first involves the intimate mixing of pulp and lyocell fiber, which can be carried out in a pulper. Usually water is added to this mixture to ensure proper dispersion. In order to adjust the water content of this initial mixture same can be passed through a station adapted to adjust the concentration, such as a mixing chest. This ensures that the mixture can be pumped to the next stages of the process and that in particular that the mixture can be evenly distributed on a web required for forwarding the not yet entangled web to the hydroentangling station. After mixing, the prepared mixture (slurry) is provided to a distribution station, which distributes the mixture in the desired amount and width onto a moving belt. The amount provided to the belt is adjusted in particular in relation with the target basis weight of the fibrous nonwoven web to be produced. The belt is typically adapted to allow in particular a dewatering step, so that the distributed slurry yields the so called wet laid material. Additional stations which further remove water, such as vacuum stations, may be provided, which also typically ensure an improved uniformity of wet laid material. Subsequently, in typical processes further drying steps are carried out, for example by using steam heated can dryers or other conventional means for drying. After these treatments the dried wet laid webs may be wound onto rolls to forward same to the hydroentanglement step, it is however also possible to directly forward the wet laid webs in accordance with procedures known in the art to the hydroentanglement treatment, and of it is of course also possible to omit some or all of the drying steps, when directly forwarding the wet laid webs to the hydroentanglement. A usual continuous process does not include a drying step before the hydroentangling step. However, a de-watering step, typically including a vacuum de-watering step, is usual for such continuous processes.

Hydroentanglement may be carried out using water beams or jets, which are arranged either on one side of the web to be entangled or on both sides of the web to be entangled. The number of water beams is not critical but two or more beams are conventional. Processes employing in total four water beams, preferably two on each side of the web, have shown to be highly suitable to produce the fibrous nonwoven webs of the present invention. Process conditions during entanglement may be selected among usual conditions known to the skilled person, such as water pressures, etc. It has been found, that in order to reproducibly prepare fibrous nonwoven webs of the present invention, the so called energy consumption (sometimes referred to spunlacing energy consumption) is a good measure to ensure that the desired target values in the fibrous nonwoven webs are achieved. This energy consumption (relating to the water beams) is a theoretical value given in kWh/kg (of dry fibrous nonwoven web) calculated on the basis of water pressure, production speed and basis weight. The calculation can be done based on the principles published in <NPL>, equation (<NUM>).

Typically energy consumption values in the range of from <NUM> to <NUM> kWh/kg are suitable in the present invention. It should however be understood that higher and/or lower values are not excluded, but that the values given above are typical values, which are given here as means of illustration, taking also the specific conditions as employed in the examples, described below, into account. Suitable ranges for the energy consumption are in particular values of from <NUM> to <NUM> kWh/kg. As already indicated above, an adjustment of energy consumption under due consideration of the basis weight and weight ratio of pulp to lyocell fiber can tailor the mechanical properties of the web produced. Employing for example, as illustrated also in the examples, a basis weight of <NUM> gsm and a ratio of pulp to lyocell fiber of <NUM>:<NUM>, tensile strength values (dry, MD) of above <NUM> N/<NUM> can be obtained using an energy consumption of <NUM> kWh/kg. Lower tensile strength values are obtained with lower energy consumption, for example less than <NUM> N/<NUM> at <NUM> kWh/kg. At the same energy consumption values tensile strength values (dry, MD) of about <NUM> and about <NUM> N/5cam, respectively can be obtained with a basis weight of <NUM> gsm but a ration of pulp to lyocell fiber of <NUM>:<NUM>. These experimental results do prove the general feasibility of concept and the modular system provided by the present invention.

Generally, as it is known to the skilled person, the energy consumption may be adjusted easily by changing production speed (speed of the moving belt moving the wet laid web through the hydroentangling station) and/or by changing the water pressure during hydroentangling. In the present invention it is, when considering these two options, preferred to increase energy consumption by increasing water pressure, compared to increasing energy consumption by decreasing production speed.

In accordance with common knowledge the webs, after having been entangled may be subjected to any desired post processing steps, such as de-watering treatments and drying treatments, employing for example vacuum de-watering units and/or through air drying units etc. The web may then be wound on a roll to be shipped to further processing steps, such as cutting to a desired size, application of additives, such as lotions for cosmetic wipes, etc. As indicated above, the webs in accordance with the present invention may be provided with two- or three-dimensional structures by embossing etc. Such processes are known to the skilled person and the respective process steps may be provided at any suitable stage of the process described above. The present invention will now be described further by means of illustrative examples.

Pulp (Canfor ECF <NUM> bleached pulp) having a fiber length of <NUM> to <NUM>, a coarseness of <NUM> to <NUM>/<NUM> and a fines content of <NUM> wt. -% was mixed in the rations further illustrated below with LENZING™ Lyocell Shortcut fibers <NUM>. 7dtex/<NUM> bright and <NUM>. 4dtex/<NUM> bright. If the Examples do not specifically identify the lyocell fibers employed those identified above with the titer of <NUM>. 4dtex were used.

Substrates were laid using a wet laid line of PILL Nassvliestechnik GmbH (<NUM>-schichtige Pilo-Schrägsiebanlage NVLA-<NUM>), dewatered, dried and wound on a roll. This roll was then unwound to deliver the not yet entangled web material to a spunlacing (hydroentangling) line comprising a pre-wetting unit, two water beams on the top side of the web and then two water beams on the bottom side of the web, vacuum boxes for dewatering and a through air dryer for drying the spunlaced material.

The following fibrous nonwoven webs were produced:.

The webs were hydroentangled with different energy consumptions of <NUM> kWh/kg (a'. )), <NUM> kWh/kg (b'. )), <NUM> kWh/kg (c'. )), <NUM> kWh/kg (d'. )), <NUM> kWh/kg (e'. )) and <NUM> kWh/kg (f'. )) respectively.

The resulting webs showed the following properties:.

These results do show, that with high pulp contents and lower basis weights very high values for WRV and in particular LAC can be obtained, while the mechanical properties are still satisfactory. Increasing the basis weight from <NUM> gsm to <NUM> gsm leads to a slight decrease in LAC but the mechanical properties increase by the factorof <NUM> or more. Increasing the content of lyocell by the factor <NUM> (weight ratio pulp to lyocell fiber <NUM>/<NUM>) leads to still high LAC values but increases the mechanical properties to levels even not achieved by commercial webs containing reinforcing/binding fibers.

In order to prove that the present invention also provides valuable products at lower basis weight, additional webs were prepared according to the following:.

The webs were hydroentangled with an energy consumption of <NUM> kWh/kg (g'. The webs did show a favorable combination of high LAC values and highly satisfactory mechanical properties.

These results do show, low basis weights and high energy consumption very high values for LAC can be obtained, while the mechanical properties are still satisfactory. Increasing the basis weight leads to a decrease in LAC but the mechanical properties increase drastically, so that even for very high pulp webs (weight ratio of pulp to lyocell fiber of <NUM>/<NUM> and <NUM>/<NUM>) very high levels of mechanical properties are obtained, even for the wet webs. From these results it can be concluded that increasing the energy consumption enables the production of low basis weight webs, even with high pulp contents which do show surprisingly high strength levels, although no reinforcing fibers or binders are employed. At the same time these webs only comprise biodegradable materials from renewable sources, so that these webs clearly can be considered as sustainable products.

In order to demonstrate the superiority of the fibrous nonwoven webs of the present invention in comparison with webs comprising other types of cellulosic fibers and/or to demonstrate the relevance of fiber titer, additional tests were run using the following webs, which were hydroentangled with an energy consumption of <NUM> kWh/kg.

In each case the webs employing the lyocell fibers did show the best mechanical properties. The best results were achieved with the lyocell fibers having a titer of <NUM> dtex, while the viscose fibers lead to a loss of mechanical strength values (dry and wet, MD) almost by the factor <NUM>. The same trend was observed when considering the mechanical strength values in cross direction (CD). These webs furthermore again showed that increasing the amount of lyocell fibers in the web leads to an increase of mechanical properties. Overall, these test runs prove that, as already outlined above, the present invention is based on a specific and unsuggested selection of the raw materials for the fibrous nonwoven webs, namely the pulp component and the fiber component, which specifically is a lyocell fiber component.

Additional test runs were made in order to prove the influence of the weight ratio of pulp to lyocell fiber at constant basis weights and constant energy consumption and the influence of energy consumption at constant basis weights and constant weight ratios of pulp to lyocell fibers. Fibrous nonwoven webs with basis weights of <NUM> and <NUM> gsm respectively were hydroentengled with an energy consumption of <NUM> kWh/kg and <NUM> kWh/kg, respectively, while changing the weight ratio of pulp to lyocell fiber from <NUM>/<NUM> to <NUM>/<NUM>, with intermediate ratios of <NUM>/<NUM>, <NUM>/<NUM> and <NUM>/<NUM>. Further samples were prepared with <NUM>/<NUM> blends, again with basis weights of <NUM> and <NUM> gsm, respectively, while changing the energy consumption from <NUM> kWh/kg to <NUM> kWh/kg, with intermediate values of <NUM> kWh/kg, <NUM> kWh/kg, and <NUM> kWh/kg for the webs with a basis weight of <NUM> gsm, and from <NUM> kWh/kg to <NUM> kWh/kg, with intermediate values of <NUM> kWh/kg, <NUM> kWh/kg, and <NUM> kWh/kg for the webs with a basis weight of <NUM> gsm.

The results show that the tensile strength values (dry and wet (MD as well as CD)) increase with increasing amounts of lyocell fiber in the webs as well as with increasing energy consumption. A comparison of the blends with increasing lyocell fiber contents shows that the best balance of properties, while considering also costs of the raw material mixture, can be achieved at weight ratios of pulp to lyocell fiber of from <NUM>/<NUM> to <NUM>/<NUM>. While the samples with a weight ratio of <NUM>/<NUM> show a slight increase in mechanical properties, the additional costs associated with the higher lyocell fiber content would lead to an unfavorable balance of cost increase to gain in mechanical properties.

The test runs made with increasing energy consumption show a similar trend, that with increasing energy consumption the mechanical properties increase. In the ranges of energy consumption evaluated each increase in energy consumption did result in a clear increase of mechanical properties, so that no levelling off of the strength increase was observed. At the same time it was observed that at an energy consumption level typically employed for the production of dispersible wipes, which are typically to be employed as flushable wet toilet paper (<NUM> kWh/kg) strength values can be obtained which lead to products being of higher value.

Also these tests prove again that the present invention, while using simple raw material mixtures based on materials from renewable sources, i.e. pulp and lyocell fibers, fibrous nonwoven webs with highly satisfactory properties can be obtained.

In order to prove the efficiency of the present invention to provide fibrous nonwoven webs which can serve as sustainable replacement products for dry industrial wipes, which do contain either polyester or polyolefin fibers, additional fibrous nonwoven webs in accordance with the present invention were prepared. These were compared to a high quality industrial wipe with a basis weight of about <NUM> gsm, tensile strength values of about <NUM> N/<NUM> (dry as well as wet, due to the high content of PET fibers in thin industrial wipe a negligible difference between dry and wet state is to be expected). This wipe did show an oil uptake value of approximately <NUM>%.

Accordingly samples with basis weights of <NUM>, <NUM> and <NUM> gsm, repectively were prepared, at blend ratios of pulp to lyocell fiber of <NUM>/<NUM> and <NUM>/<NUM>, respectively. These samples were hydroentangled with energy consumptions of <NUM> kWh/kg, <NUM> kWh/kg, and <NUM> kWh/kg and embossed or provided with three-dimensional structures by providing perforations. The results show that with increasing basis weight mechanical properties increase (dry tensile strength, MD as well as CD) to levels similar to the level shown by the commercial reference product. Neither embossing nor perforating leads to a significant decrease of mechanical values and the decrease of strength values when measured in wet state is only about <NUM>%. Overall, these fibrous nonwoven webs according to the present invention do show a balance of properties rendering them usable as sustainable replacements for commercial industrial wipes.

Claim 1:
Fibrous hydroentangled nonwoven web having a basis weight of from <NUM> to <NUM> gsm determined according to DIN EN <NUM> Part <NUM>, comprising pulp and lyocell fibers, wherein the weight ratio of pulp to lyocell fibers is from <NUM>:<NUM> to <NUM>:<NUM>, and wherein the lyocell fibers have a length of from <NUM> to <NUM> and the pulp fibers have a length of from <NUM> to <NUM>, a fiber coarseness of from <NUM> to <NUM>/<NUM> and a fines content of from <NUM> to <NUM> wt.%, and wherein the pulp and lyocell fibers are the only fibrous components present in the web.