Gas-permeable, liquid-impermeable nonwoven material
AssigneeHercules Incorporated
InventorsDavid H. Dumas, Elliott Echt
Life of this patent
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Abstract
Disclosed is a liquid-impermeable, gas-permeable nonwoven material comprising a thermally consolidated blend of (1) 5% to 30% of a first polyolefin pulp, (2) 15% to 90% of a second polyolefin pulp having a melting point at least 20.degree. C. higher than the first polyolefin pulp, and (3) 5% to 55% of a staple fiber. Also disclosed is a wet forming method for making such a nonwoven material without the use of surfactants.
Claims24
A nonwoven material comprising a thermally consolidated , wet laid blend comprising (1) from about 5% to about 30% of a first polyolefin pulp, (2) from about 15% to about 90% of a second polyolefin pulp having a melting point at least 20.degree. C. higher than the first polyolefin pulp, and (3) from about 5% to about 55% of a staple fiber, based on the total weight of the blend, said material being impermeable to liquids and permeable to gases.
A wet forming process for the preparation of a nonwoven material comprising
- (1) dispersing in water a mixture comprising (a) from about 5% to about 30% of a first polyolefin pulp, (b) from about 15% to about 90% of a second polyolefin pulp having a melting point at least 20.degree. C. higher than the first polyolefin pulp, and (c) from about 5% to about 55% of a staple fiber, based on the total weight of the material, in the presence of at least one water-soluble polymer and in the absence of a surface active agent,
- (2) forming a sheet from the aqueous dispersion,
- (3) drying, and
- (4) heating the sheet to a temperature sufficient to melt the first polyolefin pulp, said nonwoven material being impermeable to liquids and permeable to gases.
A process for preventing the passage of liquids to an object while allowing the passage of gases comprising covering the object with a nonwoven material comprising a thermally consolidated, wet laid blend comprising:
- (1) from about 5% to about 30% of a first polyolefin pulp,
- (2) from about 15% to about 90% of a second polyolefin pulp having a melting point at least 20.degree. C. higher than the first polyolefin pulp, and
- (3) from about 5% to about 55% of a staple fiber, based on the total weight of the blend.
A laminate comprising a first layer and a second layer, said second layer comprising a thermally consolidated, wet laid blend comprising
- (1) for about 5% to about 30% of a first polyolefin pulp,
- (2) from about 15% to about 90% of a second polyolefin pulp having a melting point at least 20.degree. C. higher than the first polyolefin pulp, and
- (3) from about 5% to about 55% of a staple fiber, based on the total weight of the blend,
- said laminate being impermeable to liquids and permeable to gases.
Dependencies are inferred from the claim text.