Process for the application of dye fixing agents to polyamide fiber utilizing controlled fixing agent addition

Claim 2

A process for increasing the washfastness of a fibrous article containing polyamide fibers dyed with anionic dye by treatment with an anionic dye fixing agent, said process comprising: immersing said article in a liquid bath of a solvent medium for said fixing agent, said solvent medium being selected from the group consisting of aqueous solvent mediums and substantially nonaqueous solvent mediums; heating said bath and said article in said bath to a temperature at least equal to the dyeing transition temperature of said fiber of polyamide polymer; adding said fixing agent to said bath as a liquid concentrate, at least about 33% of the total fixing agent to be applied during said process being added while said bath and said article are at a temperature at least equal to said dyeing transition temperature; and stirring said bath as the fixing agent is added to said bath to mix said concentrate into said bath to form a dilute solution of said fixing agent and to provide a flow of said dilute fixing agent solution relative to said article to cause said fixing agent to be transported to said article, said stirring further providing, on the average, essentially uniform transport of said fixing agent to said article; said fixing agent being added to the bath at an addition rate of about 0.0005 to about 0.5% fixing agent/minute based on the weight of said article.

Claim 3

The process of claim 1 wherein said fixing agent is selected from the group consisting of low molecular weight polymers with anionic groups which can associate with the nitrogen-containing groups of the polyamide polymer and form a surface layer that reduces diffusion of the dye out of the treated fiber.

Claim 4

The process of claim 1 wherein said fixing agent is selected from the group consisting of: sulfonated napthol-formaldehyde condensation products; sulfonated phenol-formaldehyde condensation products; polymers of methylacrylic acid or its alkali metal salt, and up to 70 weight percent of one or more monomers having ethylenic unsaturation and containing 2 to 20 atoms; a polymer of maleic acid or fumaric acid, or alkali metal salts thereof, and up to 70 weight percent of an ethylenically unsaturated aromatic comonomer containing 2 to 20 atoms; polymers of alpha-substituted acrylic acids or esters polymerized in the presence of a sulfonated aromatic formaldehyde condensation polymer; polymers of a sulfonated hydroxyaromatic ester of an alpha-substituted acrylic acid or acrylic acid; and mixtures thereof.

Claim 5

The process of claim 1 wherein said fixing agent is selected from the group consisting of sulfonated napthol-formaldehyde condensation products; sulfonated phenol-formaldehyde condensation products; and mixtures thereof.

Claim 6

The process of claim 1 wherein at least about 50% of said total fixing agent to be applied during said process is added while said bath and said article are at a temperature at least equal to said dyeing transition temperature.

Claim 7

The process of claim 1 wherein said polyamide polymer is selected from the group consisting of aliphatic polyamide homopolymers and copolymers.

Claim 8

The process of claim 6 wherein said aliphatic polyamide is selected from the group consisting of aliphatic polyamides containing at least one of poly(hexamethylene adipamide) or poly(ε-caproamide) polymer units in an amount greater than about 60% by weight.

Claim 9

A process for increasing the washfastness of a fibrous article containing polyamide fibers dyed with anionic dye by treatment with an anionic dye fixing agent, said process comprising: immersing said article in a liquid bath of a solvent for said fixing agent, said solvent being selected from the group consisting of aqueous solvents and substantially non-aqueous solvents, said substantially non-aqueous solvents comprising at least about 10% by volume of a water-miscible alcohol; heating said bath and said article in said bath to a temperature at least equal to the dyeing transition temperature of said fiber of polyamide polymer; adding said fixing agent to said bath as a liquid concentrate, at least about 33% of the total fixing agent to be applied during said process being added while said bath and said article are at a temperature at least equal to said dyeing transition temperature; and stirring said bath as the fixing agent is added to said bath to mix said concentrate into said bath to form a dilute solution of said fixing agent and to provide a flow of said dilute fixing agent solution relative to said article to cause said fixing agent to be transported to said article, said stirring further providing, on the average, essentially uniform transport of said fixing agent to said article; said process being performed in a dyeing machine in which said stirring provides repetitive machine cycles; said fixing agent is being added to the bath at a fixing agent addition rate such that between about 0.04% and about 7% of the total fixing agent to be applied during said process is added to said bath during a machine cycle.

Claim 10

A process for increasing the washfastness of a fibrous article containing polyamide fibers dyed with anionic dye by treatment with an anionic dye fixing agent, said process comprising: immersing said article in a liquid bath of a solvent for said fixing agent, said solvent being selected from the group consisting of aqueous solvents and substantially non-aqueous solvents, said substantially non-aqueous solvents comprising at least about 10% by volume of a water-miscible alcohol; heating said bath and said article in said bath to a temperature at least equal to the dyeing transition temperature of said fiber of polyamide polymer; adding said fixing agent to said bath as a liquid concentrate, at least about 33% of the total fixing agent to be applied during said process being added while said bath and said article are at a temperature at least equal to said dyeing transition temperature; and stirring said bath as the fixing agent is added to said bath to mix said concentrate into said bath to form a dilute solution of said fixing agent and to provide a flow of said dilute fixing agent solution relative to said article to cause said fixing agent to be transported to said article, said stirring further providing, on the average, essentially uniform transport of said fixing agent to said article; said process being performed in a dyeing machine in which said stirring provides repetitive machine cycles; said fixing agent is being added to the bath at a fixing agent addition rate such that between about 0.04% and about 7% of the total fixing agent to be applied during said process is added to said bath during a machine cycle.

Claim 11

The process of claim 8 wherein said dye fixing agent addition rate is adjusted so that an amount of fixing agent between about 0.5% and 3% of the total fixing agent to be applied during said process is added to said bath during a machine cycle.