non-woven fabric. Use of the non-woven fabric and wipe. dryer sheet as well

Face mask containing the non-woven fabric

technical field

The invention relates to a nonwoven fabric with a network of shaped bodies, the nonwoven fabric having a specific opacity of greater than or equal to 1.0% m 2 /g in the dry state. In addition, the invention relates to uses of the nonwoven and a wipe, a dryer towel and a face mask containing the nonwoven.

State of the art

Nonwoven fabrics (also referred to as nonwovens or non-woven textiles) are used in a wide range of applications. The unique properties and low manufacturing costs make them an ideal substrate for disposable or disposable products in hygiene applications such as wipers, wet wipes, face masks, diapers and others. Especially in the area of ​​wiper applications, customers have requirements regarding high opacity, sufficient mechanical strength, flexibility, thickness and high water absorption of the products. In particular, high opacity is of great importance to the end customer, as nonwoven products with too low opacity tend to be associated with low tear strength and low reliability. At the same time, however, the desire for products with a low basis weight is constantly increasing. A high level of opacity can enable a further reduction in basis weight and still convey the feeling of tear resistance and reliability to the end customer.

[0003] Although nonwovens with a high basis weight are usually also associated with high opacity, the production of nonwovens with a low basis weight, particularly in the range below about 35 g/m 2 , and at the same time high opacity poses major challenges for manufacturers.

[0004] Simple hydroentangled nonwovens (as known from EP 0473325 A1) can only be produced with great effort in low basis weights and then have a highly irregular structure and thus also opacity. Without appropriate modifications and additives, these often cannot achieve the necessary or desired opacity with low basis weights.

[0005] For example, it is known from the prior art (US 2017/0360622 A1, CN 107460787 A, CN 104556966 A) to increase the opacity of a nonwoven fabric by adding a matting agent such as titanium dioxide or zinc oxide. However, such delustrants are expensive and severely weaken the strength and flexibility of the fibers. In addition, these substances require increased process engineering effort in order to be able to be incorporated into the fibers.

[0006] Furthermore, spunbonded nonwovens are known, for example from the prior art (US Pat. No. 3,666,545 A, WO 2010/028238 A1), which are manufactured from thermoplastic synthetic polymers in a meltblown or spunbond process. However, nonwovens having such a spunbonded nonwoven require a multi-layer structure in order to be able to meet the requirements for strength and stability. The individual layers of different nonwovens are glued or fused together or provided with an additional coating in order to achieve the desired opacity of the nonwoven. However, such nonwovens generally have a low water absorption capacity due to the synthetic polymer filaments and low flexibility due to the multi-layer or coated layer structure. In addition, nonwoven fabrics comprising synthetic polymers are not biodegradable and their use in disposable or single-use products should be avoided.

Another possibility, known from the prior art (WO 2006/133037 A1, WO 2004/063434 A1), for increasing the opacity in nonwovens is the use of cross-section-modified fibers. For example, it is known to extrude the fibers through a specially shaped die and thus obtain fibers with a modified cross-section, such as hollow fibers. Although fibers of this type have increased opacity compared to fibers with a solid, rounded cross section, they are complicated in terms of process technology and are therefore expensive to produce. In addition, when synthetic polymers are used, such fibers exhibit reduced water absorption.

The nonwovens according to the invention can be produced according to a method for the direct production of nonwovens from a cellulose-containing spinning solution.

Such methods are known, for example, from the prior art (WO 98/26122 A1, WO 99/47733 A1, WO 98/07911 A1, WO 97/01660 A1, WO 99/64649 A1, WO 05/106085 A1, EP 1 358 369 A1, and EP 2 013 390 A1).

The production and extrusion of the spinning solution in such a process is preferably carried out using a direct dissolving process such as the lyocell process. In this process, cellulose is dissolved in an aqueous solution of an amine oxide (preferably NMMO - N-methylmorpholine-N-oxide) dissolved directly and formed into a spinnable spinning solution. The spinning solution is then extruded through suitable spinnerets and the cellulose dissolved in the extruded spinning solution is precipitated with a coagulant to form shaped bodies. In the case of an amine oxide, water or a mixture of water and amine oxide is particularly suitable as a coagulant. The production of such spinning solutions using the lyocell process for producing nonwovens is known, for example, from WO 98/26122 A1, US Pat. No. 7,067,444 B2 or US Pat. No. 8,012,565 B1.

Disclosure of Invention

The invention has therefore set itself the task of creating a nonwoven fabric with a low weight per unit area, which is easy to produce and has a high specific opacity without special modifications.

The invention solves the problem in that the shaped bodies are regenerated cellulosic shaped bodies and are bonded to one another via nodes to form the network, and the regenerated cellulosic shaped bodies comprise individual filament sections which extend between nodes and vary in diameter along their length and have a diameter of less than or equal to 15 μm over at least 90% of their longitudinal extent.

Are the moldings regenerated cellulosic moldings, biodegradable nonwovens can be created, which also in a

simple and reliable methods can be produced inexpensively. If the shaped bodies are also bonded to one another via nodes to form the network, a particularly dimensionally stable fleece can be created, which enables high tear strength with a low basis weight. In addition, the opacity of the fleece can advantageously be greatly increased if the regenerated cellulosic shaped bodies comprise individual filament sections extending between nodes, which vary in diameter along their length and have a diameter of less than or equal to 15 μm over at least 90% of their length. The individual filament sections, which vary in diameter, can ensure a particularly high and advantageous light scattering due to their irregular surface and thus increase the opacity of the entire nonwoven fabric. As explained above, the individual filament sections with fine diameters make it possible to cover a particularly large area with a large number of filaments per area, which in turn is conducive to a homogeneous opacity of the nonwoven fabric. In addition, the very fine diameters of less than or equal to 15 μm make it possible to increase the volume and thus reduce the basis weight without sacrificing opacity. A nonwoven fabric with a low basis weight and a specific opacity of greater than or equal to 1.0% m 2 /g can thus be created.

It is further mentioned in this connection that the formation of individual individual filament sections with diameters of greater than 15 μm is unavoidable due to the nature of the manufacturing process. However, such outliers in no way adversely affect the advantageous properties of the nonwovens according to the invention, as long as the individual filament sections have a diameter of less than or equal to 15 μm over at least 90% of their longitudinal extension. In further advantageous configurations of the invention, the individual filament sections can also have a diameter of less than or equal to 15 μm over at least 95% of their longitudinal extension.

[0015] In general, it is stated that a cohesive connection between the cellulose molecules of the regenerated cellulosic shaped bodies is understood as being a material connection between the shaped bodies in the nonwoven fabric. Such a connection can take place in particular by touching or bringing not yet fully coagulated shaped bodies (or extruded spinning solution) into contact after they have been extruded, with the cellulose molecules forming the integral connection via cohesion.

[0016] In general, it is mentioned that the opacity of the nonwoven is understood as meaning the degree of opacity or opacity. Such opacity is usually determined by measuring the light transmission of the non-woven fabric, where opacity [%] = 100% - light transmission [%].

The specific opacity of the nonwoven is defined as the opacity [%] normalized over the basis weight [g/m2] according to formula (1):

specific opacity [%-m2/g] = opacity [%] / basis weight [g/m2]. (1 )

By determining the specific opacity, the effect of increasing opacity with increasing basis weight can be normalized.

In general, it is also mentioned that the opacity of the nonwoven fabric in the dry state with a natural moisture content according to conditioning at 23 °C (± 2 °C) and 50 % (± 5 %) relative humidity for 24 hours.

The properties of a nonwoven fabric of the type mentioned above can be further advantageously improved if the regenerated cellulosic shaped bodies comprise multifilament sections which extend between nodes and consist of a plurality of essentially parallel single filament sections which are integrally bonded to one another. This is because the individual filaments connected to form the multifilament can thus contribute to stabilizing the nonwoven fabric and increasing its strength. If, in addition, the multifilament sections have a diameter of less than or equal to 100 μm over at least 90% of their longitudinal extent, it can further be ensured that the nonwoven fabric has a homogeneous appearance essentially without disturbing visible thickening. A network of shaped bodies can thus be created in the nonwoven fabric, which at the same time has thicker multifilament sections for structure and strength formation and thinner individual filament sections for increasing opacity. Such a network can have an essentially multimodal distribution of the shaped body diameter. The multifilament sections can be formed from 2 or more individual filaments after extrusion of the moldings. Here touch the not yet fully coagulated moldings and

are permanently connected by cohesion. The multifilament sections are therefore not bundles of individual filaments, but rather chemically and physically inseparably connected units.

[0020] If the regenerated cellulosic moldings form an essentially endless network without visible filament ends, a nonwoven can be provided which has less abrasion and can also build up a better contact surface. For example, contact with the skin or with a surface can be improved.

Expectations

1. Nonwoven fabric with a network (1) of shaped bodies (2), wherein the nonwoven fabric (100, 101) in the dry state has a specific opacity of greater than or equal to 1.0% m2/g, characterized in that the shaped bodies ( 2) are regenerated cellulosic shaped bodies (2) and are cohesively connected to one another via node points (3) to form the network (1), and the regenerated cellulosic shaped bodies (2) comprise individual filament sections (4) extending between node points (3), which are along vary in their diameter (7) over their longitudinal extent (6) and have a diameter (7) of less than or equal to 15 μm over at least 90% of their longitudinal extent (6).

2. Nonwoven fabric according to Claim 1, characterized in that the regenerated cellulosic shaped bodies (2) comprise multifilament sections (5) which extend between nodes (3) and consist of a plurality of materially bonded and essentially parallel individual filament sections (4), the multifilament sections (5) have a diameter (9) of less than or equal to 100 μm over at least 90% of their longitudinal extent (8).

3. Nonwoven fabric according to claim 1 or 2, characterized in that the regenerated cellulosic shaped bodies (2) form a substantially endless network (1) without visible filament ends.

4. Nonwoven fabric according to one of claims 1 to 3, characterized in that the nonwoven fabric (100, 101) is essentially free of matting agents and colorants.

5. Nonwoven fabric according to one of claims 1 to 4, characterized in that the nonwoven fabric (100, 101) consists essentially exclusively of cellulose. 2/3

6. Nonwoven fabric according to one of claims 1 to 5, characterized in that the regenerated cellulosic shaped bodies (2), in particular according to a Lyocell process, are solution-spun cellulosic shaped bodies (2).

7. Nonwoven fabric according to claim 6, characterized in that the individual filament sections (4) have a solid, in particular rounded, cross section.

8. Nonwoven fabric according to one of claims 1 to 7, characterized in that the nonwoven fabric (100, 101) is essentially free of binders or adhesives.

9. Nonwoven fabric according to one of claims 1 to 8, characterized in that the nonwoven fabric (100, 101) is essentially free of copper and/or nickel.

10. Nonwoven fabric according to claim 9, characterized in that the nonwoven fabric (100, 101) has a copper content of less than 5 ppm and/or a nickel content of less than 2 ppm.

11. Nonwoven fabric according to one of claims 1 to 10, characterized in that the individual filament sections (4) have a diameter (7) of less than or equal to 10 μm, in particular less than or equal to 7 μm, over at least 90% of their longitudinal extension (6).

12. Nonwoven fabric according to one of claims 1 to 11, characterized in that the individual filament sections (4) have an average diameter (7) of greater than or equal to 1 μm and less than or equal to 8 μm.

13. Nonwoven fabric according to one of claims 1 to 12, characterized in that the nonwoven fabric (100, 101) in the dry state has a specific opacity of greater than or equal to 1.2%-m2/g, in particular greater than or equal to 1.5%-m2 /g.

14. Nonwoven fabric according to one of claims 1 to 13, characterized in that the nonwoven fabric (100, 101) has a basis weight of less than or equal to 70 g/m2, in particular less than or equal to 35 g/m2, particularly preferably less than or equal to 20 g/m2, having.

15. Nonwoven fabric according to one of claims 1 to 14, characterized in that the nonwoven fabric (100, 101) properties and surface finishing or -

3/3

Modifying substances or processing-facilitating agents in a content of max. 1% by weight, in particular max. 0.5% by weight.

16. Nonwoven fabric according to one of claims 1 to 15, characterized in that the network (1) of regenerated cellulosic shaped bodies (2) has a plurality of interconnected layers.

17. Use of a nonwoven (100, 101) according to any one of claims 1 to 16 for the production of hygiene products, in particular absorbent layers, wipes, diapers, bandages, inserts, pads, disposable clothing and the like, and for the production of filters, industrial Products, clothing, furniture and interior design, automobiles, leisure products or products for schools and businesses.

18. Wiping cloth, face mask or drying cloth, comprising a nonwoven (100, 101) according to one of claims 1 to 16, in particular having a specific opacity of greater than or equal to 1.0%-m2/g.

19. Wiping cloth, face mask or drying cloth according to claim 18, characterized in that the non-woven fabric (100, 101) is impregnated with a lotion (210, 310, 410).

20. A wiper, face mask or dryer sheet according to claim 19 characterized in that the lotion (210, 310, 410) is substantially non-water based.