US4610678A — High-density absorbent structures

Claim 1

Independent Claim 76 words

A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of hydrophilic fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel, in a fiber/hydrogel weight ratio from about 30:70 to about 98:2; said absorbent structure having a density of from about 0.15 to about 1 g/cm 3 , a moisture content of less than about 10% by weight of the dry absorbent structure and a Gurley Stiffness value of less than 2 grams.

Claim 2

Dependent Claim 76 words

A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of hydrophilic fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel, in a fiber/hydrogel weight ratio from about 30:70 to about 98:2; said absorbent structure having a density of from about 0.15 to about 1 g/cm 3 , a moisture content of less than about 10% by weight of the dry absorbent structure and a Gurley Stiffness value of less than 2 grams.

Claim 3

Dependent Claim 19 words

An absorbent structure according to claim 1, having a fiber/hydrogel weight ratio of from about 50:50 to about 95:5.

Claim 4

Dependent Claim 19 words

An absorbent structure according to claim 1, having a fiber/hydrogel weight ratio of from about 75:25 to about 90:10.

Claim 5

Dependent Claim 20 words

An absorbent structure according to claim 1, having a density of from about 0.15 to about 0.6 g/cm 3 .

Claim 6

Dependent Claim 19 words

An absorbent structure according to claim 1, having a density of from about 0.25 to about 0.44g/cm 3 .

Claim 7

Dependent Claim 15 words

An absorbent structure according to claim 1 wherein the hydrophilic fibers are wood pulp fibers.

Claim 8

Dependent Claim 76 words

An absorbent structure according to claim 1, further comprising from about 0.01% to about 0.5% by weight of the hydrophilic fibers of a quaternary ammonium compound of the formula ##STR3## wherein R 1 and R 2 are hydrocarbyl groups containing from about 8 to about 22 carbon atoms, R 3 and R 4 are alkyl having from 1 to 6 carbon atoms; n and m are integers from 2 to about 10, and X is halogen.

Claim 9

Dependent Claim 19 words

An absorbent structure according to claim 1 which the has a Gurley Stiffness value of less than 1 g.

Claim 10

Dependent Claim 25 words

An absorbent structure according to claim 1, wherein the hydrogel particles have an average particle size of from about 30 microns to about 4 mm.

Claim 11

Dependent Claim 25 words

An absorbent structure according to claim 1, wherein the hydrogel particles have an average particle size of from about 50 microns to about 1 mm.

Claim 12

Dependent Claim 106 words

A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of wood pulp fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel in a fiber/hydrogel weight ratio of from about 75:25 to about 90:10, said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylate, co-polymers of isobutylene and maleic anhydride, and mixtures thereof, said particles having an average particle size of from about 50 microns to about 1 mm; said structure having a density of from about 0.15 to about 0.6 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 13

Dependent Claim 106 words

A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of wood pulp fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel in a fiber/hydrogel weight ratio of from about 75:25 to about 90:10, said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylate, co-polymers of isobutylene and maleic anhydride, and mixtures thereof, said particles having an average particle size of from about 50 microns to about 1 mm; said structure having a density of from about 0.15 to about 0.6 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 14

Dependent Claim 87 words

A process for making a continuous, flexible absorbent structure, comprising the following steps: (a) air-laying into a web a dry mixture of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel, said mixture having a fiber/hydrogel weight ratio of from about 30:70 to about 98:2 and a moisture content of less than about 10% by weight of the mixture; and, (b) compressing the web to a density of from about 0.15 to about 1 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 15

Dependent Claim 87 words

A process for making a continuous, flexible absorbent structure, comprising the following steps: (a) air-laying into a web a dry mixture of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel, said mixture having a fiber/hydrogel weight ratio of from about 30:70 to about 98:2 and a moisture content of less than about 10% by weight of the mixture; and, (b) compressing the web to a density of from about 0.15 to about 1 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 16

Dependent Claim 27 words

A process according to claim 12, whereby the mixture of hydrophilic fibers and hydrogel particles has a fiber/hydrogel weight ratio of from about 50:50 to about 95:5.

Claim 17

Dependent Claim 27 words

A process according to claim 12, whereby the mixture of hydrophilic fibers and hydrogel particles has a fiber/hydrogel weight ratio of from about 75:25 to about 90:10.

Claim 18

Dependent Claim 24 words

A process according to claim 12 whereby the web is compressed to a density of from about 0.15 to about 0.6 g/cm 3 .

Claim 19

Dependent Claim 24 words

A process according to claim 12 whereby the web is compressed to a density of from about 0.25 to about 0.4 g/cm 3 .

Claim 20

Dependent Claim 14 words

A process according to claim 12, wherein the hydrophilic fibers are wood pulp fibers.

Claim 21

Dependent Claim 36 words

A process according to claim 12, wherein the cross-linked polymeric hydrogel is selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates, copolymers of isobutylene and maleic anhydride, and mixtures thereof.

Claim 22

Dependent Claim 24 words

A process according to claim 12, wherein the hydrogel particles have an average particle size of from about 30 microns to about 4 mm.

Claim 23

Dependent Claim 24 words

A process according to claim 12 wherein the hydrogel particles have an average particle size of from about 50 microns to about 1 mm.

Claim 24

Dependent Claim 138 words

A process for making a flexible, substantially unbonded, absorbent structure, comprising the following steps: (a) dry mixing of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel in a weight ratio of from about 75:25 to about 90:10, said particles having an average size of from about 50 microns to about 1 mm, and said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates, copolymers of isobutylene and maleic anhydride, and mixtures thereof to form a fiber/hydrogel mixture having a moisture content of less than 10% by weight; (b) air-laying of the mixture obtained in step (a) into a web; and (c) compressing the web into a density of from about 0.15 to about 0.6 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 25

Dependent Claim 138 words

A process for making a flexible, substantially unbonded, absorbent structure, comprising the following steps: (a) dry mixing of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel in a weight ratio of from about 75:25 to about 90:10, said particles having an average size of from about 50 microns to about 1 mm, and said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates, copolymers of isobutylene and maleic anhydride, and mixtures thereof to form a fiber/hydrogel mixture having a moisture content of less than 10% by weight; (b) air-laying of the mixture obtained in step (a) into a web; and (c) compressing the web into a density of from about 0.15 to about 0.6 g/cm 3 and a Gurley Stiffness value of less than 2 grams.

Claim 26

Dependent Claim 11 words

An absorbent structure made according to the process of claim 12.

Claim 27

Dependent Claim 10 words

An absorbent product comprising the absorbent structure of claim 1.

Claim 28

Dependent Claim 35 words

A disposable diaper, comprising: (a) a liquid impervious backing sheet; (b) a hydrophobic top sheet; (c) an absorbent structure according to claim 1, said structure being placed between the backing sheet and the top sheet.

Claim 29

Dependent Claim 34 words

A disposable diaper, comprising: (a) a liquid impervious backing sheet; (b) a hydrophobic topsheet; and (c) an absorbent structure according to claim 7, said structure being placed between the backing sheet and the topsheet.

Claim 30

Dependent Claim 25 words

A disposable diaper according to claim 24, wherein the absorbent structure has a basis weight of from about 0.01 to about 0.05 g/cm 2 .

Claim 31

Dependent Claim 16 words

A disposable diaper according to claim 24 wherein the absorbent structure is wrapped in envelope tissue.

Claim 32

Dependent Claim 23 words

A disposable diaper according to claim 27 wherein the absorbent structure has a thickness of from about 0.3 mm to about 2 mm.

Claim 33

Dependent Claim 23 words

A disposable diaper according to claim 27 wherein the absorbent structure has a thickness of from about 0.5 mm to about 1 mm.

Claim 34

Dependent Claim 13 words

A disposable diaper according to claim 24 wherein the absorbent structure is hourglass-shaped.

Claim 35

Dependent Claim 29 words

A disposable diaper according to claim 24 further comprising a wood pulp fiber absorbent core which is placed between the hydrophobic top sheet (b) and the absorbent structure (c).

Claim 36

Dependent Claim 24 words

A disposable diaper according to claim 31 wherein the wood pulp fiber absorbent core is hourglass shaped and the absorbent structure (c) is rectangular.

Claim 37

Dependent Claim 35 words

A sanitary napkin comprising: (a) a liquid impervious backing sheet; (b) a hydrophobic top sheet; (c) an absorbent structure according to claim 1, said structure being placed between the backing sheet and the top sheet.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-09-08	1990-03-10	1990-09-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-09-08	1994-03-10	1994-09-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-09-08	1998-03-10	1998-09-09	$7700.00	Window Closed / Lapsed

High-density absorbent structures

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