EP0301804A2 — Method and apparatus for production of nonwoven f…

Claim 1

Independent Claim 163 words

A process for producing a nonwoven fibrous web from an aqueous solution of a polymer composition which is water insoluble and superabsorbent upon curing, which comprises:- (a) forming the polymer solution into water soluble filaments; (b) contacting the filaments with a primary air stream having a velocity effective to partially attenuate and to partially dry the filaments; (c) contacting the filaments in a fiber-forming zone with a secondary air stream having a velocity effective to further attenuate and to fragment the filaments into fibers, to further dry the fibers and to transport the fibers to a web-forming zone; (d) collecting the fibers in reticulated web-form in the web-forming zone; and (e) curing the web in a curing zone; wherein the temperature and air stream velocities are controlled with respect to ambient humidity and water content of the fiber during fiber and web formation such that during collection the fibers remain substantially non-sticking and cure in the curing step to a soft, integral web.

Claim 2

Dependent Claim 163 words

A process for producing a nonwoven fibrous web from an aqueous solution of a polymer composition which is water insoluble and superabsorbent upon curing, which comprises:- (a) forming the polymer solution into water soluble filaments; (b) contacting the filaments with a primary air stream having a velocity effective to partially attenuate and to partially dry the filaments; (c) contacting the filaments in a fiber-forming zone with a secondary air stream having a velocity effective to further attenuate and to fragment the filaments into fibers, to further dry the fibers and to transport the fibers to a web-forming zone; (d) collecting the fibers in reticulated web-form in the web-forming zone; and (e) curing the web in a curing zone; wherein the temperature and air stream velocities are controlled with respect to ambient humidity and water content of the fiber during fiber and web formation such that during collection the fibers remain substantially non-sticking and cure in the curing step to a soft, integral web.

Claim 3

Dependent Claim 32 words

The process of claim 1 wherein the fibers formed from the polymer solution are collected on a forming wire and the forming wire carrying the fibers moves continuously through the curing zone.

Claim 4

Dependent Claim 14 words

The process of claim 1 or claim 2 including (f) compacting the cured web.

Claim 5

Dependent Claim 12 words

The process of claim 3 wherein the compacting includes embossing the web.

Claim 6

Dependent Claim 40 words

The process of any one of claims 1 to 4 wherein the temperature and air stream velocities are controlled in the fiber-forming web-forming zones whereby the moisture content of the fibers prior to curing is less than 20% by weight.

Claim 7

Dependent Claim 24 words

The process of any one of claims 1 to 5 wherein the primary air stream entrains and transports the filaments to the fiber-forming zone.

Claim 8

Dependent Claim 36 words

The process of any one of claims 1 to 6 wherein the velocity of the primary air is at least about 500 fpm and the velocity of the secondary air is at least about 300 fpm.

Claim 9

Dependent Claim 61 words

The process of any one of claims 1 to 7 wherein the polymer solution comprises about 25 to 60% polymer solids and the polymer composition comprises a blend of (1) a copolymer of at least one α,β-unsaturated carboxylic monomer and at least one monomer copolymerizable therewith and (2) a crosslinking agent wherein the crosslinking functionality comprises hydroxyl or heterocyclic carbonate groups.

Claim 10

Dependent Claim 25 words

The process of claim 8 wherein the copolymer comprises about 20-80 weight % pendant carboxylic acid groups and about 80-20 weight % pendant carboxylate groups.

Claim 11

Dependent Claim 48 words

The process of claim 8 or claim 9 wherein the copolymer is a copolymer of maleic anhydride and at least one of styrene and iso butylene, and the crosslinking agent is propylene carbonate, ethylene glycol, propylene glycol, 1,4-butane diol, diethylene glycol, glycerol, pentaerythritol, meso-erythritol or any mixture thereof.

Claim 12

Dependent Claim 60 words

The process of claim 8, claim 9 or claim 10 wherein the process conditions are as follows: primary air velocity: about 500 to 8000 fpm; secondary air velocity: at least about 3000 fpm; secondary air temperature: about 25 to 140°C; temperature of curing zone: about 150 to 275°C; residence time of web in curing zone: about 0.5 to 35 minutes.

Claim 13

Dependent Claim 117 words

The solution of any one of claims 1 to 10 wherein the polymer solution comprises about 35 to 55% polymer solids, the polymer composition comprises a blend of (1) a partially neutralized copolymer of maleic anhydride and at least one of styrene and isobutylene, and (2) a crosslinking amount of propylene carbonate, ethylene glycol, propylene glycol, 1,4-butane diol, diethylene glycol, glycerol, pentaerythritol, meso-erythritol or any mixture thereof, and the process conditions are as follows: primary air velocity: about 500 to 8000 fpm; secondary air velocity: at least about 3000 fpm; secondary air temperature: about 25 to 140°C; temperature of curing zone: about 150 to 270°C; residence time of web in curing zone: about 0.5 to 35 minutes.

Claim 14

Dependent Claim 16 words

A nonwoven web produced by the process claimed in any one of claims 1 to 12.

Claim 15

Dependent Claim 130 words

Nonwoven fibrous web producing apparatus, comprising, in combination: (a) means for forming an aqueous polymer solution into filaments; (b) first air supply means positioned to direct an air stream upon and to partially attenuate and to partially dry the filaments; (c) a housing having opposing inlet and outlet means; (d) second air supply means positioned to direct an air stream upon the filaments for further attenuation and for fragmentation thereof, and to further dry and carry the fragments through the inlet and outlet of the housing; (e) a foraminous surface at the outlet of the housing for collecting the fragments in web form; (f) suction means adjacent to the foraminous surface positioned to entrain the fragments on the foraminous surface; and (g) means for curing the web on the surface.

Claim 16

Dependent Claim 130 words

Nonwoven fibrous web producing apparatus, comprising, in combination: (a) means for forming an aqueous polymer solution into filaments; (b) first air supply means positioned to direct an air stream upon and to partially attenuate and to partially dry the filaments; (c) a housing having opposing inlet and outlet means; (d) second air supply means positioned to direct an air stream upon the filaments for further attenuation and for fragmentation thereof, and to further dry and carry the fragments through the inlet and outlet of the housing; (e) a foraminous surface at the outlet of the housing for collecting the fragments in web form; (f) suction means adjacent to the foraminous surface positioned to entrain the fragments on the foraminous surface; and (g) means for curing the web on the surface.

Claim 17

Dependent Claim 32 words

Apparatus as in claim 14 wherein the second air supply means is positioned substantially normal to the path of the attenuated filaments, and including temperature and humidity control means in the housing.

Claim 18

Dependent Claim 36 words

Apparatus as in claim 14 or claim 15 wherein the filament forming means includes a die having a plurality of die holes, and the first air supply means comprises air tubes positioned adjacent the die holes.

Claim 19

Dependent Claim 50 words

The apparatus as in claim 14, claim 15 or claim 16 wherein the foraminous surface comprises a moving wire belt adapted to carry the web, and the curing means comprises an oven chamber adapted for passage therethrough of the belt carrying the web, the apparatus further including web take-up means.

Claim 20

Dependent Claim 41 words

Apparatus as in claim 17 including air exhaust means to effect an air pressure differential to hold the web in place on the belt during initial passage through the oven chamber and to exhaust air from the secondary air supply means.

Claim 21

Dependent Claim 20 words

Apparatus as in any one of claims 14 to 18 further including web compacting means positioned after the curing means.

Claim 22

Dependent Claim 96 words

Apparatus as claimed in claim 19 further including web take-up means positioned between the curing means and the web compacting means, wherein the foraminous surface comprises a moving wire belt adapted to carry the web, and wherein the curing means comprises an oven chamber adapted for passage therethrough of the belt carrying the web, the apparatus further including a third air supply means and air exhaust means connected to the third air supply means to thereby effect an air pressure differential to hold the web in place on the belt during passage through an oven chamber.

Method and apparatus for production of nonwoven fibrous articles

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