Breathable, liquid inpervious backsheet for absorptive devices

Claim 2

In a disposable absorbtive device having an absorbent body and a backsheet, an improved breathable, liquid impervious backsheet, comprising: the combination of two adjacent hydrophobic layers to form an effective breathing portion of the improved backsheet; the first layer being liquid permeable under pressure and having a low void volume; the second layer being liquid permeable and having a high void volume, whereby the combination of the two layers prevents the passage of liquid while permitting the passage of vapors and gasses.

Claim 3

The improved backsheet claimed in claim 1 wherein the first layer is a liquid impervious film having perforations therein, whereby the first layer is made liquid permeable under pressure.

Claim 4

The improved backsheet claimed in claim 2 wherein the average projected diameter of the perforations is in the range of from about 10 to about 300 micrometers and the open area of the first layer in the effective breathing portion is from about 0.01 to about 5.0 percent of the nominal area of the first layer coextensive with the effective breathing portion.

Claim 5

The improved backsheet claimed in claim 2 wherein the average projected diameter of the perforations is in the range of from about 10 to about 200 micrometers and the open area of the first layer in the effective breathing portion is from about 0.01 to about 2.0 percent of the nominal area of the first layer coextensive with the effective breathing portion.

Claim 6

The improved backsheet claimed in claim 2 wherein the average projected diameter of the perforations is in the range of from about 10 to about 100 micrometers and the open area of the first layer in the effective breathing portion is from about 0.01 to about 1.0 percent of the nominal area of the first layer coextensive with the effective breathing portion.

Claim 7

The improved backsheet claimed in claim 2 wherein the first layer has a permanent strain of 15% or less after an elongation of 30%.

Claim 8

The improved backsheet claimed in claim 6 wherein the average projected diameter of the perforations is in the range of from about 10 to about 100 micrometers and the open area of the first layer in the effective breathing portion is from about 0.01 to about 1.0 percent of the nominal area of the first layer coextensive with the effective breathing portion.

Claim 9

In a disposable absorptive device having an absorbent body and a backsheet, an improved breathable, liquid impervious backsheet, comprising: the combination of two adjacent hydrophobic layers to form an effective breathing portion of the improved backsheet; the first layer being liquid permeable and having a low void volume; the second layer being liquid permeable and having a high void volume; whereby the combination of the two layers prevents the passage of liquid while permitting the passage of vapors and gases; wherein said first layer is a liquid impervious film which has a permanent strain of 15% or less after an elongation of 30% and which has a plurality of bosses therein, said bosses being provided with perforations, whereby said first layer is made liquid permeable under pressure, and wherein the projected diameter of said perforations is in the range of from about 10 to about 100 micrometers and the open area of said first layer in said effective breathing portion is from about 0.01 to about 1.0 percent of the nominal area of said first layer coextensive with said effective breathing portion. 9. The improved backsheet claimed in claim 8 wherein the average height of the bosses is at least 50 micrometers.

Claim 10

The improved backsheet claimed in claim 8 wherein the bosses are oriented toward the absorbent body.

Claim 11

The improved backsheet claimed in claim 8 wherein the second layer is intermediate the first layer and the absorbent body.

Claim 12

The improved backsheet claimed in claim 11 wherein the bosses are oriented toward the absorbent body.

Claim 13

The improved backsheet claimed in claim 1 wherein the air permeability of the second layer is at least 10 cfm./sq. ft. at a pressure differential of 0.5 inches water.

Claim 14

The improved backsheet claimed in claim 1 wherein the void volume of second layer is at least 60 percent.

Claim 15

The improved backsheet claimed in claim 14 wherein the second layer comprises a fibrous web.

Claim 16

The improved backsheet claimed in claim 15 wherein the second layer comprises a creped tissue and a hydrophobic material, the surfaces of the fibers comprising the tissue being coated with the hydrophobic material.

Claim 17

The improved backsheet claimed in claim 14 wherein the second layer is foam-like having a series of interconnecting channels therethrough.

Claim 18

The improved backsheet claimed in claim 17 wherein the second layer is a flexible, open-celled, polymeric, foam material.

Claim 19

The improved backsheet claimed in claim 1 wherein the second layer is intermediate the first layer and the absorbent body.

Claim 20

In a disposable absorptive device having an absorbent body and a backsheet, an improved breathable, liquid impervious backsheet, comprising: a combination of a first and a second layer to form an effective breathing portion of the improved backsheet, the second layer being interposed between the first layer and the absorbent body; the first layer comprising: A. a liquid-impervious, hydrophobic, polymeric film, the film having a permanent strain of 15% or less after an elongation of 30%; B. a plurality of bosses in the film; the height of the bosses being at least 50 micrometers; C. a plurality of perforations in the film, the perforations being located within the bosses, the average projected diameter of the perforations being from about 10 to about 100 micrometers, the perforations being substantially uniformly distributed in the portion of the first layer coextensive with the effective breathing portion such that the open area of that portion of the first layer is from about 0.01 to about 1.0 percent of the effective breathing portion; the second layer comprising: a fibrous web and a hydrophobic material, the surfaces of the fibers comprising the web being coated with the hydrophobic material, the coated web having a void volume of at least 60 percent, and the hydrophobic fibrous structure having an air permeability of at least 10 cfm./sq. ft. at a pressure differential of 0.5 inch of water; whereby the passage of liquid through the effective breathing portion is substantially prevented and the transmission of vapors and gasses therethrough can occur.

Claim 21

In a disposable absorptive device having an absorbent body and a backsheet, an improved breathable, liquid impervious backsheet, comprising: a combination of a first and a second layer to form an effective breathing portion of the improved backsheet, the second layer being interposed between the first layer and the absorbent body; the first layer comprising: A. a liquid-impervious, hydrophobic, polymeric film, the film having a permanent strain of 15% or less after an elongation of 30%; B. a plurality of bosses in the film; the height of the bosses being at least 50 micrometers; C. a plurality of perforations in the film, the perforations being located within the bosses, the average projected diameter of the perforations being from about 10 to about 100 micrometers, the perforations being substantially uniformly distributed in the portion of the first layer coextensive with the effective breathing portion such that the open area of that portion of the first layer is from about 0.01 to about 1.0 percent of the effective breathing portion; the second layer comprising: a fibrous web and a hydrophobic material, the surfaces of the fibers comprising the web being coated with the hydrophobic material, the coated web having a void volume of at least 60 percent, and the hydrophobic fibrous structure having an air permeability of at least 10 cfm./sq. ft. at a pressure differential of 0.5 inch of water; whereby the passage of liquid through the effective breathing portion is substantially prevented and the transmission of vapors and gasses therethrough can occur.