Superabsorbent polymer having a capacity increase
The present invention relates to a particulate superabsorbent polymer comprising a monomer and an internal crosslinker agent wherein the particulate superabsorbent polymer has a Centrifuge Retention Capacity Increase of 2 g/g or more as set forth herein in the Centrifuge Retention Capacity Increase Test. The present invention further relates to a superabsorbent polymer comprising an internal crosslinker agent comprising a silane compound comprising at least one vinyl group or one allyl group attached to a silicon atom, and at least one Si—O bond. The present invention further relates to an absorbent article that includes such particulate superabsorbent polymers.
1. An absorbent article comprising: (a) a liquid pervious topsheet; (b) a liquid impervious backsheet; (c) a core positioned between (a) and (b), said core comprising about 10% to 100% by weight of a particulate superabsorbent polymer and 0% to about 90% by weight of hydrophilic fiber material; (d) optionally a tissue layer positioned directly above and below said core (c); and (e) an acquisition layer positioned between (a) and (c); wherein the particulate superabsorbent polymer comprises a monomer selected from an ethylenically unsaturated carboxylic acid, ethylenically unsaturated carboxylic acid anhydride, salts or derivatives thereof, and an internal crosslinker agent wherein the internal crosslinker agent comprises a silane compound comprising at least one vinyl group or allyl group and at least one Si—O bond wherein the vinyl group or allyl group is directly attached to a silicon atom, wherein the superabsorbent polymer has a Centrifuge Retention Capacity Increase of 2 g/g or more based on
CRC Increase=CRC(rt,5 hr)−CRC(rt,0.5 hr)
and wherein CRC Increase measures the increase in the CRC that occurs and is calculated as the difference between the second CRC and first CRC and rt refers to room temperature.
2. The absorbent article of claim 1 wherein the particulate superabsorbent polymer has a Centrifuge Retention Capacity Increase of from about 2 g/g to about 50 g/g.
3. The absorbent article claim 1 wherein said silane compound is selected from vinyltriisopropenoxy silane, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, diethoxymethylvinyl silane, and polysiloxane comprising at least two vinyl groups.
4. The absorbent article of claim 1 further comprising a second internal crosslinker.
5. The absorbent article of claim 4 wherein the second internal crosslinker is selected from polyethylene glycol monoallyl ether acrylate, ethoxylated trimethylol propane triacrylate, or polyethylene glycol diacrylate.
6. The absorbent article of claim 1 wherein the particulate superabsorbent polymer has a Centrifuge Retention Capacity Increase of from about 2 g/g to about 40 g/g.
7. The absorbent article of claim 1 wherein the particulate superabsorbent polymer has a Centrifuge Retention Capacity Increase Rate of from about 0.4 g/g/hr to about 10 g/g/hr based on
CRC Increase Rate=CRC(rt,5 hr)−CRC(rt,0.5 hr)
wherein the CRC Increase Rate measures the ability of the particulate superabsorbent polymer to gain additional CRC over the time when contacted with the liquid.
8. The absorbent article of claim 1 wherein the particulate superabsorbent polymer has a Centrifuge Retention Capacity measured at body temperature (CRC(bt)) and a Centrifuge Retention Capacity measured at room temperature (CRC(rt)) wherein CRC(bt) and CRC(rt) have the same testing time and CRC(bt) is about 2 g/g to 20 g/g higher than CRC(rt).