Water soluble fibers with post process modifications and articles containing same
A method of treating a fiber includes admixing a fiber comprising a polymer comprising at least one of a vinyl acetate moiety or a vinyl alcohol moiety and having a degree of hydrolysis less than 100% with a hydrolysis agent solution to form a mixture so as to increase the degree of hydrolysis of at least a portion of the fiber.
1 . A method of treating a fiber, said method comprising:
admixing a fiber comprising a polymer comprising at least one of a vinyl acetate moiety or a vinyl alcohol moiety and having a degree of hydrolysis less than 100% with a hydrolysis agent solution to form a mixture so as to increase the degree of hydrolysis of at least a portion of the fiber, wherein the fiber does not dissolve in the hydrolysis agent solution and admixing a fiber increases the degree of hydrolysis of at least a portion of the fiber, wherein admixing a fiber with the hydrolysis agent solution is performed under conditions sufficient to provide a post-process fiber having a transverse cross-section with an increasing gradient in the degree of hydrolysis from an interior region of the post-process fiber to a surface region of the post-process fiber.
2 . The method according to claim 1 , further comprising heating the mixture of the fiber and the hydrolysis agent solution.
3 . The method according to claim 1 , wherein the fiber is admixed with the hydrolysis agent solution under conditions sufficient to provide at least one of a predetermined degree of hydrolysis or a predetermined degree of hydrolysis increase to the at least a portion of the fiber.
4 . The method according to claim 1 , wherein the fiber is admixed with the hydrolysis agent solution for a period of time in a range of from 1 minute to 48 hours.
5 . The method according to claim 1 , wherein the fiber is admixed with the hydrolysis agent solution at a temperature in a range of 10° C. to 100° C.
6 . The method according to claim 1 , wherein the polymer has a degree of hydrolysis greater than 79% and less than 96% prior to admixing the fiber with the hydrolysis agent solution.
7 . The method according to claim 1 , wherein the fiber is water-soluble after admixing the fiber with the hydrolysis agent solution.
8 . The method according to claim 1 , wherein the hydrolysis agent solution comprises a hydrolysis agent and a solvent.
9 . The method according to claim 8 , wherein the hydrolysis agent comprises a metallic hydroxide, a metal hydride, a sulfite, sulfur dioxide, a dithionate, a thiosulfate, a hydrazine, oxalic acid, formic acid, ascorbic acid, dithiothreitol, a phosphite, a dihypophosphite, phosphorous acid, sulfuric acid, sulphonic acid, hydrochloric acid, ammonium hydroxide, water, or combinations thereof.
10 . The method according to claim 8 , wherein the hydrolysis agent comprises a metallic hydroxide.
11 . The method according to claim 10 , wherein the metallic hydroxide comprises an alkali metal hydroxide, an alkaline earth metal hydroxide, a main group metal hydroxide, or combinations thereof.
12 . The method according to claim 8 , wherein the hydrolysis agent comprises sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, trialkyltin hydroxide, or combinations thereof.
13 . The method according to claim 8 , wherein the hydrolysis agent is provided in an amount of 0.2% (w/w) to 75% (w/w) based on a weight of the solvent.
14 . The method according to claim 8 , wherein the fiber is not soluble in the solvent.
15 . The method according to claim 8 , wherein the solvent comprises a polar solvent.
16 . The method according to claim 8 , wherein the solvent comprises one or more solvents selected from the group consisting of: n-propanol, acetone, ethanol, N-methylpyrrolidone, methanol, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, formic acid, water, and combinations thereof.
17 . The method according to claim 8 , wherein the solvent comprises a nonpolar solvent.
18 . The method according to claim 8 , wherein the solvent comprises an alcohol that is a liquid under admixing conditions.
19 . The method according to claim 8 , wherein the solvent comprises a mixture of a first solvent and a second solvent.
20 . The method according to claim 19 , wherein the first solvent comprises a polar solvent and the second solvent comprises a nonpolar solvent.
21 . The method according to claim 19 , wherein the first solvent has a first dielectric constant and the second solvent has a second dielectric constant and the first dielectric constant is higher than the second dielectric constant.
22 . The method according to claim 21 , wherein a difference between the first dielectric constant and the second dielectric constant is at least 3.
23 . The method according to claim 1 , further comprising admixing an activator with the fiber and the hydrolysis agent solution.
24 . The method according to claim 1 , wherein the polymer comprises at least one of a vinyl acetate moiety or a vinyl alcohol moiety comprising a polyvinyl alcohol homopolymer, a polyvinyl acetate homopolymer, a polyvinyl alcohol copolymer, or combinations thereof.
25 . The method according to claim 24 , wherein the polyvinyl alcohol copolymer is a copolymer of vinyl acetate and vinyl alcohol.
26 . The method according to claim 24 , wherein the polyvinyl alcohol copolymer comprises an anionically modified copolymer.
27 . The method according to claim 26 , wherein the anionically modified copolymer comprises a carboxylate, a sulfonate, or combinations thereof.
28 . The method according to claim 1 , wherein the fiber further comprises an additional polymer.
29 . The method according to claim 28 , wherein the additional polymer is selected from the group consisting of: polyvinyl alcohol, polyvinyl acetate, polyacrylate, a water-soluble acrylate copolymer, polyvinyl pyrrolidone, polyethylenimine, pullulan, guar gum, gum Acacia, xanthan gum, carrageenan, starch, modified starch, polyalkylene oxide, polyacrylamide, polyacrylic acid, cellulose, cellulose ether, cellulose ester, cellulose amide, polycarboxylic acid, polyaminoacid, polyamide, a gelatin, dextrin, copolymers of the foregoing, and combinations of any of the foregoing additional polymers or copolymers.
30 . The method according to claim 1 , wherein admixing the fiber with the hydrolysis agent solution is performed under conditions sufficient to provide the post-process fiber having the transverse cross-section having a structure including a core and a sheath, wherein the core comprises the polymer with a first degree of hydrolysis and the sheath comprises the polymer with a second degree of hydrolysis greater than the first degree of hydrolysis.
31 . The method according to claim 1 , wherein the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for 1 minute to 24 hours.
32 . The method according to claim 1 , wherein the fiber comprises a copolymer of vinyl alcohol and vinyl acetate having a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for 12 hours to 24 hours.
33 . The method according to claim 1 , wherein the fiber comprises an anionically modified copolymer having a carboxylate or sulfonate modification and a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for 12 hours to 24 hours.
34 . The method according to claim 1 , wherein the fiber comprises a copolymer of vinyl alcohol and vinyl acetate having a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for 1 hour to 12 hours.
35 . The method according to claim 1 , wherein the fiber comprises an anionically modified copolymer having a carboxylate or sulfonate modification and a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing a fiber comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for 1 hour to 12 hours.
36 . The method according to claim 1 , wherein the fiber comprises a copolymer of vinyl alcohol and vinyl acetate having a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for up to 1 hour.
37 . The method according to claim 1 , wherein the fiber comprises an anionically modified copolymer having a carboxylate or sulfonate modification and a degree of hydrolysis of 88%, 92%, or 96%, the hydrolysis agent solution comprises sodium hydroxide and methanol, and admixing comprises immersing the fiber in the hydrolysis agent solution, and heating the mixture of the fiber in the hydrolysis agent solution to a temperature of 30° C. to 60° C. for up to 1 hour.
38 . The method of claim 1 , further comprising:
contacting a surface of the fiber with the hydrolysis agent solution to increase the degree of hydrolysis of the polymer at the surface of the fiber.
39 . The method according to claim 38 , wherein contacting a surface of the fiber with the hydrolysis agent solution comprises immersion, spraying, transfer coating, wicking, foaming, brushing, rolling, humidification, vapor deposition, printing, or combinations thereof.
40 . The method according to claim 38 , wherein contacting a surface of the fiber with the hydrolysis agent solution is performed after formation of the fiber as part of a continuous inline process.
41 . The method according to claim 38 , wherein contacting a surface of the fiber with the hydrolysis agent solution is performed while the fiber is in motion.
42 . The method according to claim 38 , wherein contacting a surface of the fiber with the hydrolysis agent solution is performed in a batch by a batch process.
43 . The method according to claim 38 , wherein the fiber comprises at least one of a staple fiber, a staple yarn, a fiber fill, needle punch fabrics, bonding fibers, or combinations thereof.