Bleaching and dyeing; fluid treatment and chemical modification – Cleaning or laundering – Scouring – degreasing or bowking
Reexamination Certificate
1999-11-09
2001-09-18
Del Cotto, Gregory (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Cleaning or laundering
Scouring, degreasing or bowking
C008S137000, C510S283000, C510S284000, C510S336000, C510S337000, C510S339000, C510S340000, C510S488000, C510S491000
Reexamination Certificate
active
06290732
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to laundry processes for removing ink soil from porous substrates. More specifically, the invention relates to a process for removing ink soil from woven fabrics such as towels. The invention uses a pre-treatment step containing an alkyl fatty acid ester to improve ink soil removal efficacy.
BACKGROUND OF THE INVENTION
Ink soil removal is a special problem in the laundry industry. Wiper towels and fabric sheeting which have been soiled with ink, i.e. where ink has penetrated the fabric, normally requires use of organic solvents such as mineral spirits, or mixed nonylphenol ethoxylate (NPE) and high caustic. Use of volatile solvents such as mineral spirits leads to fire hazards and contributes to poor air quality in laundry plants.
U.S. Pat. No. 5,340,493 describes a one-step ink-cleaning composition for removing inks from printer hard surfaces, e.g. rollers, metals, rubber surfaces while using woven polyester ink washing blankets which automatically remove ink from such ink transfer rollers and press parts. The composition uses tall oil fatty acid esters and nonionics but requires the use of mineral spirits.
U.S. Pat. No. 5,340,495; WO 95/18843 and EP 527 315 also describe similar one-step ink-cleaning compositions for removing inks from printer blankets as in the above '493 patent. The compositions employ fatty acid methyl esters, nonionic surfactants and possibly glycol solvents and volatile solvents like mineral spirits. No chelants are described in these references.
We have found that by employing a chelant and using an alkyl fatty acid ester in a pre-treatment step, improved ink removal results were found without the need for using volatile organic solvents.
SUMMARY OF THE INVENTION
Accordingly, in its broadest sense, the invention can be found in a process for removing ink soil from porous substrates having the steps of first conditioning the substrate with an alkyl fatty acid ester, cleaning the substrate with a conventional detergent composition, and rinsing the substrate with water; wherein an effective amount of a chelating agent can be added during the conditioning step or the cleaning step or between these steps.
In a preferred embodiment, the invention is found in a laundry process for removing ink soil from a porous textile substrate which has the steps of pre-treating the substrate in a soak cycle containing an alkyl fatty acid ester, treating the substrate in a wash cycle including a conventional detergent composition and an effective amount of a chelating agent, and treating the substrate to one or more water rinse cycles.
In another preferred embodiment, the invention is found in a laundry process for removing ink soil from a porous textile substrate having the steps of pre-treating the substrate in a soak cycle containing an alkyl fatty acid ester and an effective amount of a chelating agent, treating the substrate in a wash cycle including a conventional detergent composition, and treating the substrate to one or more water rinse cycles.
DETAILED DESCRIPTION OF THE INVENTION
The processes described in the invention involve a prewash treatment which includes contacting an ink soiled substrate with a composition containing an alkyl fatty acid ester. It has been found that this pretreatment step substantially improves ink soil removal during a subsequent conventional washing step. Addition of the ester directly to the wash liquor has little or no effect.
While the alkyl fatty acid ester must be added to the pretreatment step, no such limitation exists for the chelating agents described in the invention. These chelants can be added to the pretreatment step, to the wash step or in between the two steps. Typically, pretreatment contacting steps are about 5 minutes in length while commercial wash steps are typically about 20 minutes in length.
Such a pretreatment may be either as a pre-spotter or as a pre-detergent flush in the cleaning sequence in a washing machine or as a pre-soak step prior to washing. The pre-treatment serves to condition the soil and makes it more susceptible to mechanical action in a subsequent washing step with traditional detergents.
The alkyl fatty acid ester can be applied to the substrate, i.e. the textile fabric, in the form of a liquid concentrate or in a dilute aqueous dispersion in, e.g., a wash cycle. A liquid concentrate has about 30 to 100 wt-% of an alkyl fatty acid ester while the dilute solution contains about 0.01 to about 5 wt-% of the alkyl fatty acid ester. The liquid concentrate may be applied directly on the substrate by pouring or spraying.
Accordingly, the invention is most broadly found in a process for removing ink soil from porous substrates having the steps of first conditioning the substrate with an alkyl fatty acid ester, cleaning the substrate with a conventional detergent composition, and rinsing the substrate with water; wherein an effective amount of a chelating agent can be added during the conditioning step or the cleaning step or between these steps.
In a preferred embodiment, the invention is found in a laundry process for removing ink soil from a porous textile substrate which has the steps of pre-treating the substrate in a soak cycle containing an alkyl fatty acid ester, treating the substrate in a wash cycle including a conventional detergent composition and an effective amount of a chelating agent, and treating the substrate to one or more water rinse cycles.
In another preferred embodiment, the invention is found in a laundry process for removing ink soil from a porous textile substrate having the steps of pre-treating the substrate in a soak cycle containing an alkyl fatty acid ester and an effective amount of a chelating agent, treating the substrate in a wash cycle including a conventional detergent composition, and treating the substrate to one or more water rinse cycles.
Alkyl Fatty Acid Esters
The process of the invention begins with a pretreatment step with a composition containing an alkyl fatty acid ester. Possible alkyl groups include from C
1
to C
8
straight or branched hydrocarbon chains, while methyl fatty acid esters are preferred.
The esters can be formed with a variety of fatty acids, including from C
8
to C
24
fatty acids. However, C
12
-C
18
fatty acids are preferred. Esters can also include mono, di and triglycerides. A preferred ester is available commercially as SOY GOLD®, which is methyl soyate. This is the methyl ester of soybean oil, which consists generally of triglycerides of oleic, linoleic, linolenic and other acids.
Generally, the fatty acid ester is used in an aqueous solution containing from about 0.01 to about 5, preferably about 0.01 to about 2 wt-% of the alkyl fatty acid ester.
Chelating Agents
The processes described in the invention utilize a chelating agent which is included in one of the first two processing steps or between such steps in a separate cycle. Preferred chelating agents include an aminocarboxylic acid, an organic phosphonate, an inorganic phosphonate or a mixture thereof. Preferred chelating agents include ethylenediaminetetraacetic acid and nitrilotriacetic acid, and their salts.
Chelating agents usefull in the invention also include amino-tris-(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, hexarnethylenediamine-tetra-(methylenephosphonic acid), diethylenetriamine-penta-(methylenephosphonic acid), or alkali metal salts thereof. These phosphonates are part of the DEQUEST® series which are available commercially from Monsanto; St. Louis, Miss.
Typically, these chelating agents are used at a concentration of about 0.01 to about 5, preferably about 0.01 to about 2 wt-%.
Conventional Detergent Compositions
The processes of the invention utilize a conventional detergent composition after the initial pretreatment step. Conventional detergent compositions may include an alkalinity source, surfactants, builders or sequestrants and minor ingredients.
Surfactants
Useful anionic surfactants include the water soluble salts, preferably the alkali metal, ammonium and alkylo
Hei Robert D. P.
Smith Kim R.
Wiseth Wendy
Cotto Gregory Del
Ecolab Inc.
Merchant & Gould P.C.
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