GLASS FIBER FREE FILTER MEDIUM WITH A DENSIFIED LAYER MADE OF SYNTHETIC FIBERS

Abstract

A multi-layered filter medium with a densified layer made of synthetic fibers is useful for filtering liquids. A method for its production involves providing multiple layers, densifying a layer, and joining the multiple layers.

Claims

1: A filter medium, comprising: a first layer, a second layer having many pores with a diameter of 4-13 μm, and optionally, a third layer.

2: The filter medium according to claim 1, wherein the second layer comprises a dry-laid nonwoven.

3: The filter medium according to claim 1, wherein the second layer is one selected from the group consisting of a spunbond layer, a meltblown layer, and a combination of a spunbond layer and a meltblown layer.

4: The filter medium according to claim 1, wherein the first layer comprises cellulose.

5: The filter medium according to claim 1, wherein the filter medium comprises the third layer.

6: The filter medium according to claim 1, wherein the second layer is a densified layer.

7: The filter medium according to claim 1, wherein the second layer comprises polyester fibers.

8: The filter medium according to claim 1, wherein the second layer comprises a densified meltblown layer.

9: The filter medium according to claim 1, wherein air permeability increases from the first layer to the second layer, and optionally, from the second layer to the third layer.

10: The filter medium according to claim 1, wherein a basis weight increases from the second layer to the first layer, and optionally, from the third layer to the first layer.

11: A method, comprising: filtering a liquid with the filter medium according to claim 1, wherein during the filtering, a flow direction of the liquid is from the second layer to the first layer, and optionally, from the third layer to the first layer.

12: The method according to claim 11, wherein the liquid is fuel, oil, or water.

13: A method for producing the filter medium according to claim 1, the method comprising: providing the first layer, the second layer, and optionally, the third layer, densifying the second layer, and joining the first layer, the second layer, and optionally, the third layer.

Description

EXAMPLES

General Example 1

[0152] In Table 1 an exemplary embodiment of a three layer arrangement is disclosed. The first layer is a cellulose saturated base layer, followed by a densified meltblown layer, based on PBT (polybutylene terephthalate). The densification step was performed by means of a flat calander. The layer 3 is a meltblown layer based on PBT.

TABLE-US-00001 TABLE 1 Total Layers Layer 1 Layer 2 Layer 3 medium Type of Cellulose Densified Meltblown nonwoven saturated MB layer layer base layer, wetlaid Polymer Cellulose PBT PBT fiber 25 1 2-4 diameter (μm) Thickness 0.41 0.2 0.2 0.87 (mm) Air 5 15-25 150 3-5 permeability (l/m.sup.2s) Basis weight 211 80 55 370 (g/m.sup.2)

[0153] Flow Direction: Layer 3 (inflow side)—Layer 2—Layer 1 (outflow side)

Example 2

[0154] In comparison to Example 1, the second layer comprises the densified meltblown layer of example 1 and an additional spunbond layer. The spunbond layer of the second layer comprises PBT fibers with a fiber diameter of 15 μm, a basis weight of 20 g/m.sup.2 and a thickness of 0.09 mm. The meltblown layer and the spunbond layer of the second layer are densified together with a flat calender.

[0155] Flow direction: Third Layer (inflow side)—Second Layer—First Layer (outflow side)

Comparative Example 1 and 2

[0156] First Layer: Cellulose saturated base layer, wetlaid

[0157] Second Layer: Polyester meltblown fibers, densified by calendaring

[0158] Third Layer: Meltblown layer

[0159] Flow direction: Third Layer (inflow side)—Second Layer—First Layer (outflow side)

TABLE-US-00002 TABLE 2 % of Average fibers fiber with a diameter diameter in the <1 μm meltblown inthe Initial layer meltblown efficiency of the layer (%) Air Max. Many Basis Thickness second of the for particles perm. Pore Pores Weight (mm) at layer second ≥4.0 μm Sample (1/m.sup.2 s) (μm) (μm) (g/m.sup.2) 0.1 bar (μm) layer [ISO 19438] Example 1 18.6 11 7.5 60 0.165 1.44 39.44 99.80 (S4261) Example 2 17.9 11 7 80 0.180 1.40 38.99 99.78 Comparative 75.4 18 14 59 0.163 1.96 6.88% 90.39 Example 1 Comparative 76.1 20 16 73 0.189 2.85 1.93% 81.75 Example 2

[0160] Example 1, Example 2, Comparative Example 1 and Comparative Example 2 all comprise polyester meltblown fibers in the Second Layer.

[0161] As it can be seen in Table 2, the filter medium according to the present invention shows very good efficiency values though it does not contain glass fibers.