Composite absorbent structures with nonwoven substrates with improved lamination integrity
In accordance with the present invention, a composite absorbent structure is formed by air laying an absorbent core comprising cellulosic fibers, typically wood pulp fibers. The absorbent core may include superabsorbent polymeric material (SAP), for enhanced liquid absorption and retention. The present invention contemplates that a nonwoven fabric layer be provided which comprises polymeric fibrous material, either in staple length or filamentary form. A composite material is formed in which the cellulosic fibers are hydrogen bonded to form an absorbent core and the nonwoven fabric layer is laminated to this hydrogen bonded layer, without adding additional non-cellulosic bonding agents (the cellulosic fibers themselves act as their own bonding agents) either to the cellulosic layer or between the cellulosic layer and the nonwoven.
1 . A method of forming a composite absorbent structure, comprising the steps of:
air-laying an absorbent core comprising cellulosic fibers;
providing a nonwoven fabric layer comprising polymeric fibrous material;
providing cooperating calender rolls; and
calender bonding said nonwoven fabric layer and said absorbent core.
2 . A method of forming a composite absorbent structure in accordance with claim 1 , wherein
one of said calender rolls defines an embossed pattern, said bonding step including contacting said nonwoven fabric layer with said calender roll defining said embossed pattern.
3 . A method of forming a composite absorbent structure in accordance with claim 1 , wherein
said nonwoven fabric layer comprises resin-bonded fibers.
4 . A method of forming a composite absorbent structure in accordance with claim 1 , including:
air-laying an additional layer, and positioning said additional layer adjacent said nonwoven fabric layer, opposite said absorbent core.
5 . A method of forming a composite absorbent structure, comprising the steps of:
a. airlaying an absorbent core comprising cellulosic fibers without additional bonding materials in the airlaid portion;
b. providing a nonwoven fabric layer comprising polymeric fibrous material, without additional bonding material disposed between said nonwoven and said airlaid portion, and
c. providing cooperating heated calender rolls, and calender bonding said nonwoven fabric layer and said absorbent core, wherein the resulting bond had delamination strength exceeding 0.5N.
6 . A method of forming a composite absorbent structure in accordance with claim 5 wherein:
said nonwoven fabric layer is selected from the group consisting of resin-bond nonwoven fabric, spunbond nonwoven fabric, and through-air bonded nonwoven fabric.
7 . A method of forming a composite absorbent structure in accordance with claim 5 , wherein:
one of said calender rolls defines an embossed pattern, said bonding step including contacting said nonwoven fabric layer with said calender roll defining said embossed pattern.
8 . A composite absorbent structure formed in accordance with the method of claim 5 .
9 . A composite structure consisting of the following:
a. a stratum layer comprising cellulosic fibers containing no additional bonding materials; and
b. at least one nonwoven fabric layer comprising polymeric fibrous material, in which the two layers are bonded together without additional bonding materials between the stratum layer and the nonwoven fabric layer, and where the delamination strength exceeds 0.5 N.
10 . A composite structure in accordance with claim 9 , wherein:
said nonwoven fabric layer comprises a resin-bonded nonwoven fabric.
11 . A composite structure in accordance with claim 9 , wherein:
said stratum layer comprises superabsorbent polymer.
12 . A composite structure in accordance with claim 9 , wherein:
said nonwoven fabric layer comprises a spunbond fabric.
13 . A composite structure in accordance with claim 9 , including:
at least one tissue layer positioned adjacent said stratum layer.
14 . A composite structure in accordance with claim 9 , including:
a heat-bondable layer positioned adjacent said stratum layer.
15 . A composite structure in accordance with claim 9 , wherein:
said nonwoven fabric layer comprises a through-air bonded nonwoven fabric.