Composite nonwoven sheet material

1. A composite nonwoven sheet material comprising pulp fibers,

a reinforcement material, and microfibers, wherein the sheet material comprises:

one pulp-enriched first outer layer including at least 80 wt. % of pulp fibers in an outermost 5% of a thickness of the sheet material,

one microfiber-enriched second outer layer including at least 60 wt. % of microfibers in an outermost 5% of a thickness of the sheet material, and

wherein the reinforcement material comprises spun-laid filaments and is interposed as a reinforcement material layer between the pulp-enriched first outer layer and the microfiber-enriched second outer layer,

wherein the pulp fibers and the microfibers penetrate the reinforcement material,

wherein the composite nonwoven sheet material has bulk pores having a maximum pore volume distribution at a pore radius between 5 and 30 μm and which has surface pores having a maximum pore volume distribution at a pore radius between 25 and 40 μm,

wherein the composite nonwoven sheet material is a hydroentangled fibrous web comprising the reinforcement material layer having a first side and a second side, the reinforcement material being interposed between pulp fibers applied on the first side of the reinforcement material and microfibers or splittable fibers for providing the microfibers applied on the second side of the reinforcement material, and

wherein the composite nonwoven sheet material has a liquid absorbance capacity ranging between 5.5 and 8 grams of liquid per gram of composite nonwoven sheet material.

2. The sheet material of claim 1 , wherein the pulp fibers have fiber lengths between 1 and 6 mm and the microfiber-enriched second outer layer includes at least 90 wt. % of microfibers fibers in the outermost 5% of the thickness of the sheet material.

3. The sheet material of claim 1 , wherein the microfibers have a mass density of 1 Dtex or less.

4. The sheet material of claim 1 , wherein the microfibers have a length of 18 mm or less.

5. The sheet material of claim 1 , wherein the reinforcement material comprises synthetic filaments of a thermoplastic polymer.

6. The sheet material of claim 1 , wherein the sheet material comprises 25-80 wt. % of pulp fibers, 10-40 wt. % of reinforcement material and 10-40 wt. % of microfibers.

7. The sheet material of claim 6 , wherein the sheet material comprises 40-65 wt. % of pulp fibers, 15-30 wt. % of reinforcement material and 15-30 wt. % of microfibers.

8. A process of producing the composite nonwoven sheet material of claim 1 , comprising:

forming the fibrous web comprising the reinforcement material layer having a first side and a second side, the reinforcement material being interposed between the pulp fibers applied on the first side of the reinforcement material and the microfibers applied on the second side of the reinforcement material; and

hydroentangling the fibrous web to form the composite nonwoven sheet material.

9. The process of claim 8 , wherein the fibrous web is manufactured in a process comprising:

providing the reinforcement material layer having a first side and a second side;

applying pulp fibers on the first side of the reinforcement material by wet laying, dry laying or air laying;

hydroentangling the reinforcement material provided with the pulp fibers applied on the first side of the reinforcement material; and

applying microfibers or splittable fibers for providing the microfibers on the second side of the reinforcement material by wet laying, dry laying or air laying to obtain the fibrous web.

10. The process of claim 8 , wherein the fibrous web is manufactured in a process comprising:

providing a layer comprising pulp fibers by wet laying, dry laying or air laying,

applying the reinforcement material layer on one side of the layer comprising pulp fibers by wet laying, dry laying or air laying;

hydroentangling the layer comprising pulp fibers provided with the reinforcement material layer; and

applying microfibers or splittable fibers for providing the microfibers on the reinforcement material layer by wet laying, dry laying or air laying to obtain the fibrous web.

11. The process of claim 8 , wherein the fibrous web is manufactured in a process comprising:

providing a layer comprising microfibers or splittable fibers for providing the microfibers by wet laying, dry laying or air laying,

applying the reinforcement material layer on one side of the layer comprising the microfibers, by wet laying, dry laying or air laying;

hydroentangling the layer comprising microfibers provided with the reinforcement material; and

applying pulp fibers on the reinforcement material layer by wet laying, dry laying or air laying to obtain the fibrous web.

12. The process of claim 8 which further comprises:

two hydroentanglement steps at different sides of the fibrous web.

13. A wipe comprising the composite nonwoven sheet material of claim 1 .

14. The process of claim 9 , which further comprises:

two hydroentanglement steps at different sides of the fibrous web.

15. The process of claim 10 , which further comprises:

two hydroentanglement steps at different sides of the fibrous web.

16. The process of claim 11 , which further comprises:

two hydroentanglement steps at different sides of the fibrous web.

17. The sheet material of claim 2 , wherein the microfibers have a mass density of 1 Dtex or less,

wherein the microfibers have a length of 18 mm or less,

wherein the reinforcement material comprises synthetic filaments of a thermoplastic polymer, and

wherein the sheet material comprises 40-65 wt. % of pulp fibers, 15-30 wt. % of reinforcement material and 15-30 wt. % of microfibers.

18. The sheet material of claim 17 , wherein the synthetic filaments of a thermoplastic polymer comprise a polyolefin, a polyester or a polylactide.

19. The sheet material of claim 1 , wherein the pulp-enriched first outer layer includes at least 90 wt. % of pulp fibers in the outermost 5% of the thickness of the sheet material.

20. The sheet material of claim 1 , wherein the composite nonwoven sheet material has a total basis weight ranging between 50 and 100 g/m 2 .