Ion-sensitive hard water dispersible polymers and applications therefor

A method of making an ion-sensitive polymer, comprising:

• forming a hydrophilically/hydrophobically balanced mixture of three or more monomers, wherein at least one monomer contains one or more hydrophilic moieties, and at least one monomer contains one or more hydrophobic moieties, and wherein the mixture comprises:
• AMPS or NaAMPS, acrylic acid, butyl acrylate, and 2-ethylhexyl acrylate;
• and
• polymerizing the mixture;
• wherein the polymer is insoluble in neutral salt solution containing at least about 0.3 weight percent salt, said salt comprising one or more monovalent or multivalent ions;
• and wherein the polymer is soluble in tap water containing one or more multivalent ions.

A nonwoven product comprising:

• at least about 50 weight percent fibers from about 0.1 to 15 m in length, and
• from about 5 to about 50 weight percent of a binder composition comprising an ion-sensitive polymer comprising
• a first repeat unit derived from a monomer selected from styrenesulfonic acid (SS), a sodium salt of styrenesulfonic acid (NaSS), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), a sodium salt f 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS), vinylsulfonic acid, a sodium salt of vinylsulfonic acid, and combinations thereof;
• a second repeat unit derived from a monomer selected from acrylic acid, a sodium salt of acrylic acid, methacrylic acid, a sodium salt o methacrylic acid, and combinations thereof;
• and
• a third repeat unit derived from a monomer selected from at least one alkyl acrylate, at least one alkyl methacrylate, and combination thereof;
• wherein the product is not substantially water-dispersible in a salt solution having a multivalent ion concentration greater than about 500 ppm, further wherein the product is water-dispersible in a salt solution having a multivalent ion concentration less than about 200 ppm.

A method of making an ion-sensitive polymer, comprising:

• forming a hydrophilically/hydrophobically balanced mixture of three or more monomers, wherein at least one monomer contains one or more hydrophilic moieties, and at least one monomer contains one or more hydrophobic moieties;
• wherein the monomer mixture comprises:
• a first monomer selected from styrenesulfonic acid (SS), a sodium salt of styrenesulfonic acid (NaSS), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), a sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS), vinylsulfonic acid, a sodium salt of vinylsulfonic acid, and combinations thereof;
• a second monomer selected from acrylic acid, a sodium salt of acrylic acid, methacrylic acid, a sodium salt of methacrylic acid, and combinations thereof;
• a third monomer selected from at least one alkyl acrylate, at least one alkyl methacrylate, and combinations thereof;
• and polymerizing the mixture;
• wherein the polymer is substantially insoluble in a neutral salt solution containing at least about 0.3 weight percent salt, said salt comprising one or more monovalent or multivalent ions;
• and wherein the polymer is substantially soluble in tap water containing one or more multivalent ions.