Manufacture of absorbent paper with low charge density imidazolinium containing debonder compositions
Absorbent sheet is manufactured utilizing a low charge density debonder composition comprising an imidazolinium surfactant-containing constituent selected from the group consisting of: (i) cationic imidazolinium surfactants with alkylalkenylhydroxy substitution; (ii) zwitterionic imidazolinium surfactants; and (iii) an ion paired surfactant mixture including a zwitterionic imidazolinium surfactant and a cationic surfactant and, in admixture with the imidazolinium surfactant-containing constituent, (iv) a nonionic surfactant.
1. A cationic imidazolinium surfactant of the formula:
wherein:
R 1 is H, methyl, ethyl, or propyl;
R 2 is a hydroxy substituted alkylalkenyl moiety having from 11 to 21 carbon atoms;
R 3 is an ethylene or propylene bridging group;
R 4 is an amidoalkenylalkyl moiety bearing a pendant hydroxyl group having from 12 to 22 carbon atoms;
p is 1 or 2; and
X is selected from halides, sulfates, carboxylates and phosphates.
2. The cationic imidazolinium surfactant according to claim 1 , wherein R 2 is:
3. The cationic imidazolinium surfactant according to claim 1 , wherein R 4 is:
4. A debonder composition for absorbent paper manufacture comprising a cationic imidazolinium surfactant of claim 1 in admixture with a nonionic surfactant.
5. The debonder composition according to claim 4 , wherein the debonder composition comprises from 5 to 45 wt. % of cationic imidazolinium surfactant and from 65 to 95 wt. % of nonionic surfactant.
6. The debonder composition according to claim 4 , wherein the debonder composition exhibits a charge density of 0.20 meq/g or less.
7. The debonder composition according to claim 6 , wherein the debonder composition exhibits a charge density of from 0.10 meq/g to 0.20 meq/g.
8. A method of making absorbent sheet comprising:
(a) preparing an aqueous furnish of papermaking fibers;
(b) incorporating a debonder composition into the aqueous furnish, said debonder composition comprising:
(i) an imidazolinium surfactant according to claim 1 , and,
(ii) in admixure with the imidazolinium surfactant, a nonionic surfactant;
(c) incorporating a cationic wet strength resin into the aqueous furnish; and
(d) forming the papermaking furnish into absorbent sheet.
9. The method of making absorbent sheet according to claim 8 , wherein the debonder composition exhibits a charge density of from −0.1 to 0.3 meq/g.
10. The method of making absorbent sheet according to claim 9 , wherein the debonder composition exhibits a charge density of 0.25 meq/g or less.
11. The method of making absorbent sheet according to claim 10 , wherein the debonder composition exhibits a charge density of from 0.175 to 0.225 meq/g.
12. The method according to claim 8 , wherein the cationic wet strength resin is incorporated into the aqueous furnish at a level of from 2.5 to 30 lbs/ton of papermaking fiber.
13. The method according to claim 8 , wherein the cationic wet strength resin is incorporated into the aqueous furnish at a level of from 5 to 25 lbs/ton of papermaking fiber.
14. The method according to claim 8 , wherein the cationic wet strength resin comprises a polyamidoamine epichlorohydrin permanent wet strength resin.
15. The method according to claim 8 , wherein the cationic wet strength resin comprises a glyoxylated polyacrylamide temporary wet strength resin.
16. The method according to claim 8 , wherein the debonder composition is incorporated into the aqueous furnish at a level of from 1 to 30 lbs debonder composition per ton of papermaking fiber.
17. The method according to claim 8 , wherein the debonder composition is incorporated into the aqueous furnish at a level of from 2 to 25 lbs debonder composition per ton of papermaking fiber.
18. The method according to claim 8 , wherein the debonder composition is incorporated into the aqueous furnish at a level of from 2 to 16 lbs debonder composition per ton of papermaking fiber.